Introduction to Fiber Optic Pigtails

During the process of fiber optic cable installation, cable connection is important to ensure the low attenuation and low return loss of signal transmission between cable and equipment. And fiber optic pigtail is a commonly used component for the connection of optical network. It is a piece of cable terminated with fiber optic connectors at one end and no connector at the other end. In this way, the connector side can be linked to the equipment and the other side can be fused with optical cable fibers. This article will emphasize on the types of fiber optic pigtails and their applications.

Here are two classifications of fiber optic pigtails. Firstly classified by connectors, fiber optic pigtails has seven types including E2000, LC, SC, ST, FC, MU and MTRJ. Secondly classified by fibers, fiber optic pigtails has two types as single-mode and multimode.

Classification of Connector


1)LC fiber optic pigtail uses the LC connector developed by Lucent Company. LC connector is now one of the most popular connectors in the world. A 1.25mm ceramic ferrule makes LC fiber optic pigtail a better choice for low cost but high precision signal transmission.


2) SC fiber optic pigtail uses the SC connector developed by Nippon Telegraph and Telephone. SC connector has a ceramic ferrule of 2.5 mm. Its light weight and cost-effective features enable different applications of SC fiber optic pigtail.



3)ST fiber optic pigtail uses the ST connector developed by American Telephone & Telegraph. ST connector has a 2.5mm bayonet-styled ferrule. It is one of the eldest generations of fiber optic connectors. But it is still used for many fiber optic applications, especially for multimode fiber optic communications.


4)FC fiber optic pigtail uses the FC connector developed by Nippon Electric Company. The connector features the screw type structure and high precision ceramic ferrule. FC fiber optic pigtail is usually used for general fiber optic applications.


Classification of Fiber Types

Single-mode fiber and multimode fiber are both used for fiber optic pigtails. The single-mode fiber optic pigtail has a 9/125 micron core size. SC, LC, ST, FC and E2000 connectors are all fit for this kind of fiber. As for multimode fiber optic pigtails, there are two different core sizes. One is 62.5/125 micron of OM1, and the other is 50/125 micron of OM2, OM3, OM4. SC, LC, ST, FC connectors are adaptable to multimode fiber optic pigtails.


Fiber optic pigtail sometimes has multiple fiber strands, including 4 fibers, 6 fibers, 8 fibers, 12 fibers, 24 fibers, 48 fibers and so on. This helps the effective interconnection and cross-connect in various applications. Since fiber optic pigtail supports fusion splicing, it is often used with devices like optical distribution frames, splice closures and cross cabinets.


In summary, fiber optic pigtail is a cable that only one end is terminated with connectors. The other end can be melted with optical fiber for a permanent connection. You may choose the adaptable fiber optic pigtail from the perspective of connector types, fiber types, strand numbers, etc. Hope this article can provide a little help.

Comparison Between CWDM & DWDM Technology

For a better signal transmission in fiber-optic communication, different kinds of technologies are applied to the industry. Wavelength-division multiplexing (WDM) is one of the commonly used technologies which multiplexes a number of optical carrier signals onto a single optic fiber by using different wavelengths of laser light. That is to say, WDM enables two or more than two wavelength signals to transmit through different optical channels in the same optical fiber at the same time.


In the WDM system, there are two types of divisions – CWDM (coarse wavelength division multiplexing) and DWDM (dense wavelength division multiplexing). They are both using multiple wavelengths of laser light for signal transmission on a single fiber. However, from the aspects of channel spacing, transmission reach, modulation laser and cost, CWDM and DWDM still have a lot of differences. This article will focus on these distinctions and hope you can have a general understanding about CWDM and DWDM technology.

Channel Spacing

As their names suggest, the words “coarse” and “dense” reveal the difference in channel spacing. CWDM has a wider spacing than DWDM. It is able to transport up to 16 wavelengths with a channel spacing of 20 nm in the spectrum grid from 1270 nm to 1610 nm. But DWDM can carry 40, 80 or up to 160 wavelengths with a narrower spacing of 0.8 nm, 0.4 nm or 0.2 nm from the wavelengths of 1525 nm to 1565 nm (C band) or 1570 nm to 1610 nm (L band). It is no doubt that DWDM has a higher performance for transmitting a greater number of multiple wavelengths on a single fiber.


Transmission Reach

Since the wavelengths are highly integrated in the fiber during light transmission, DWDM is able to reach a longer distance than CWDM. The amplified wavelengths provide DWDM with the ability of suffering less interference over long-haul cables. Unlike DWDM system, CWDM is unable to travel unlimited distance. The maximum reach of CWDM is about 160 kilometers but an amplified DWDM system can go much further as the signal strength is boosted periodically throughout the run.

Modulation Laser

CWDM system uses the uncooled laser while DWDM system uses the cooling laser. Laser cooling refers to a number of techniques in which atomic and molecular samples are cooled down to near absolute zero through the interaction with one or more laser fields. Cooling laser adopts temperature tuning which ensures better performance, higher safety and longer life span of DWDM system. But it also consumes more power than the electronic tuning uncooled laser used by CWDM system.


Because the range of temperature distribution is nonuniform in a very wide wavelength, so the temperature tuning is very difficult to realize, thus using the cooling laser technique increases the cost of DWDM system. Typically, DWDM equipment is four or five times more expensive than CWDM equipment.


CWDM and DWDM are both coming from the WDM technology that is capable of conveying multiple wavelengths in a single fiber. But with different characteristics, people should think twice before choosing the CWDM or DWDM system. CWDM usually costs less but its performance is far behind DWDM. Both your requirements and budget need to be taken into consideration. Moreover, the WDM products including CWDM mux/demux module, DWDM mux/demux module and optical splitter are highly welcome in the market.

Guide to Fusion Splicer Selection

Optic fiber is now widely applied to networks around the globe. When it comes to actual operation, connecting fibers is a necessary task. And fusion splicer is an effective tool for fiber optic splicing. But choosing the right type of fusion splicer is still a challenge. In this article, we will talk about how to find the most matching fusion splicer.

Before discussing about different types of fusion splicer, let’s first have a look at the working principle and specific function of a fusion splicer. The fusion splicer is the device that uses heat to melt the ends of two optic fibers and combines them together into one fiber. By using the fusion splicer, the joint is permanent so that light signals can pass from one fiber to another with little link loss. The heating source of a fusion splicer can be a laser, a gas flame, a tungsten filament or a electric arc. And the most popular heating source at present is electric arc.

Nowadays, there are two types of fusion splicer according to different aligning systems. One is called the core alignment fusion splicer, the other is cladding alignment fusion splicer. If you can figure out the differences between these two types of fusion splicer, finding a right fusion splicer is no longer a problem.

Core Alignment Fusion Splicer

Core alignment is the most welcome fusion splicing technology at present. The splicer combines the image and light detection systems which can view the fibers cores in order to measure and monitor core position. Fiber cores are put in V-grooves and are aligned horizontally (X-axis), vertically (Y-axis) and in/out (Z-axis). The type of fusion splicer is adaptable for all kinds of fibers, such as single-mode or multimode fiber, good or bad fiber and splicing old fiber to new fiber. It is much more expensive but provides a more precised alignment.


Cladding Alignment Fusion Splicer

Cladding alignment is also called as passive alignment or fixed V-groove type. This type of fusion splicer relies on the accurate pre-alignment of fiber V-grooves that grip the outer surface or cladding of the fiber. Fiber cores are adjusted inwards and outwards. This type of fusion splicer is only available for multimode fiber or good single-mode fibers. As to cladding alignment fusion splicer, the cost is lower and alignment is faster, but its demand for the quality of fiber is higher or else will cause a lot of losses.


Suggestions For Fiber Optic Splicing

Though the two types of fiber optic splicing are different, the methods for better splicing are common. Here are some suggestions for fiber optic splicing:

1. Clean the fusion splicer before splicing. Any invisible contamination will cause tremendous problems when splicing the fibers.

2. In order to increase the alignment speed for fusion splicer, it is important to maintain and operate other tools, such fiber cleaver. A good cleaving will save time for splicing and decrease fiber loss.

3. Make sure the fusion parameters are adjusted minimally and methodically. The changes of parameters will also generate problems for your desired setting.


Selecting a suitable fusion splicer is beneficial to the splicing process. You may consider your needs and affordable cost to find the right fusion splicer. Core alignment fusion splicer has a better performance but a higher price than cladding alignment fusion splicer. Please choose your ideal fusion splicer wisely and do not forget to follow the normative operation for your splicing.

What is FTTx Network?


Since the customers have demanded for a more intensive bandwidth, the telecommunication carriers must seek to offer a matured network convergence and enable the revolution of consumer media device interaction. Hence, the emergence of FTTx technology is significant for people all over the world. FTTx, also called as fiber to the x, is a collective term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. With different network destinations, FTTx can be categorized into several terminologies, such as FTTH, FTTN, FTTC, FTTB, FTTP, etc. The following parts will introduce the above terms at length.


FTTx is commonly associated with residential FTTH (fiber to the home) services, and FTTH is certainly one of the fastest growing applications worldwide. In an FTTH deployment, optical cabling terminates at the boundary of the living space so as to reach the individual home and business office where families and officers can both utilize the network in an easier way.


In a FTTN (fiber to the node) deployment, the optical fiber terminates in a cabinet which may be as much as a few miles from the customer premises. And the final connection from street cabinet to customer premises usually uses copper. FTTN is often an interim step toward full FTTH and is typically used to deliver advanced triple-play telecommunications services.


In a FTTC (fiber to the curb) deployment, optical cabling usually terminates within 300 yards of the customer premises. Fiber cables are installed or utilized along the roadside from the central office to home or office. Using the FTTC technique, the last connection between the curb and home or office can use the coaxial cable. It replaces the old telephone service and enables the different communication services through a single line.


In a FTTB (fiber to the building) deployment, optical cabling terminates at the buildings. Unlike FTTH which runs the fiber inside the subscriber’s apartment unit, FTTB only reaches the apartment building’s electrical room. The signal is conveyed to the final distance using any non-optical means, including twisted pair, coaxial cable, wireless, or power line communication. FTTB applies the dedicated access, thus the client can conveniently enjoy the 24-hour high speed Internet by installing a network card on the computer.


FTTP (fiber to the premise) is a North American term used to include both FTTH and FTTB deployments. Optical fiber is used for an optical distribution network from the central office all the way to the premises occupied by the subscriber. Since the optical fiber cable can provide a higher bandwidth than copper cable over the last kilometer, operators usually use FTTP to provide voice, video and data services.

FTTx Network Applications

With its high bandwidth potential, FTTx has been closely coupled with triple play of voice, video and data services. And the world has now evolved beyond triple play to a converged multi-play services environment with a high bandwidth requirement. Applications like IPTV, VOIP, RF video, interactive online gaming, security, Internet web hosting, traditional Internet and even smart grid or smart home are widely used in FTTx network.


FTTx technology plays an important part in providing higher bandwidth for global networks. According to different network architectures, FTTx is divided into FTTH, FTTN, FTTC, FTTB, FTTP, etc. FS.COM provides FTTx solutions and tutorials for your project, please visit FS.COM for more information.

Introduction to Fiber Optic Adapter

A small equipment used for connecting optical fiber cables together is often called as fiber optic adapter or fiber optic coupler. Although they may shape differently, they have the same function. A fiber optic adapter allows fiber optic cables to be attached to each other singly or in a large network, permitting many devices to communicate at once. According to different shapes and structures, fiber optic adapters can be classified in several types, such as FC fiber optic adapter, SC fiber optic adapter, ST fiber optic adapter, LC fiber optic adapter and so on. And this article will particularly introduce these four kinds of fiber optic adapters.


FC Fiber Optic Adapter

FC fiber optic adapter uses a metal sleeve to strengthen its outer structure and can be fastened by a turnbuckle. It also adopts the ceramic pins as its butt end. Therefore, FC fiber optic adapter is able to sustain a stable optical and mechanical performance for a long time. It can be divided into square type, oval type and round type in single-mode and multimode versions. FC fiber optic adapter is easy to operate but sensitive to dust, so it has been enhanced today by using spherical butt end without changing its external structure.

SC Fiber Optic Adapter

Covered with a rectangular shell, SC fiber optic adapter has the same configuration and size of the coupling pin cover as FC fiber optic adapter. From its structures, SC fiber optic adapter can be classified into simplex standard, duplex standard and shuttered standard. From its materials, metal and plastic are commonly used for SC fiber optic adapter. SC fiber optic adapter enables a high precision alignment with a low insertion, return loss and back reflection.

ST Fiber Optic Adapter

ST fiber optic adapter has a key snap-lock structure to ensure accuracy when connecting the cables together. The repeatability and durability of ST fiber optic adapter is improved by the metal key. With a precised ceramic or copper cover, ST fiber optic adapter can also keep a high optical and mechanical performance for a long time. It has two standards of simplex and duplex and uses the metal or plastic housing.

LC Fiber Optic Adapter

LC fiber optic adapter adopts the modular jack latch mechanism which is easy to operate. Using the smaller pins and sleeves, LC fiber optic adapter greatly increases the density of fiber optic connector. There are three types of LC fiber optic adapter in simplex, duplex and quad structures.

Applicable End Faces

Different fiber optic adapters supports different ends faces. PC (physical contact), UPC (ultra physical contact) and APC (angle physical contact) are the polish style used for fiber optic adapters. ST fiber optic adapter is only available with PC and UPC styles. But except ST, the rest three fiber optic adapters support all the polish styles. Moreover, the color of fiber optic adapters can be used to define different end faces of PC, UPC and APC. For example, as for SC and LC fiber optic adapters, there are cream, blue and green colors which correspond to PC, UPC and APC end faces.


In order to help the signal transmission, fiber optic adapter is widely used for telecommunications system, cable TV network, LAN (local area network), WAN (wide area network), FTTH (fiber to the home), video transmission and instrument testing. It is no doubt that fiber optic adapter is of great help for network communications.


Fiber optic adapter provides convenience for fiber cable connections. FC, SC, ST, LC fiber optic adapters are parts of the adapter family and are widely adopted in practical use. Small device like fiber optic adapter really helps a lot for different applications in life, because it greatly improves the working efficiency.

Overview of Single-mode Fiber Types

According to the light transmission mode, optic fibers can be classified into single-mode and multimode. It’s easy to categorize multimode fiber into four types of OM1, OM2, OM3 and OM4. However, when it comes to single-mode, it may not be as simple as you think. The classification of single-mode fiber is much more complicated than multimode fiber. ITU-T G.65x series and IEC 60793-2-50 (published as BS EN 60793-2-50) are two primary sources for single-mode fiber specification. This article will mainly focus on the ITU-T G.65x series.

The following table introduces 19 ITU-T specifications of single-mode fiber:

Name Type
ITU-T G.652 ITU-T G.652.A, ITU-T G.652.B, ITU-T G.652.C, ITU-T G.652.D
ITU-T G.653 ITU-T G.653.A, ITU-T G.653.B
ITU-T G.654 ITU-T G.654.A, ITU-T G.654.B, ITU-T G.654.C
ITU-T G.655 TU-T G.655.A, ITU-T G.655.B, ITU-T G.655.C, ITU-T G.655.D, ITU-T G.655.E
ITU-T G.656 ITU-T G.656
ITU-T G.657 ITU-T G.657.A, ITU-T G.657.B, ITU-T G.657.C, ITU-T G.657.D

Each type has its own area of application and the evolution of these optical fiber specifications reflects the evolution of transmission system technology from the earliest installation of single-mode optical fiber to the present day. Choosing the right one for your project can be vital in terms of performance, cost, reliability and safety. Now, let’s have a look at the differences of G.65x series specifications for single-mode fiber respectively.


The ITU-T G.652 fiber is known as standard SMF (single-mode fiber) and is the most commonly deployed fiber. It comes in four variants (A, B, C, D). A and B have a water peak. C and D eliminate the water peak for full spectrum operation. The G.652.A and G.652.B fibers are designed to have a zero-dispersion wavelength near 1310 nm, therefore they are optimized for operation in the 1310nm band. They can also operate in the 1550nm band, but it is not optimized for this region due to the high dispersion. These optical fibers are usually used within LAN, MAN and access network systems. The more recent variants (G.652.C and G.652.D) feature a reduced water peak that allows them to be used in the wavelength region between 1310 nm and 1550 nm supporting Coarse Wavelength Division Multiplexed (CWDM) transmission.



G.653 fiber was developed to address this conflict between best bandwidth at one wavelength and lowest loss at another. It uses a more complex structure in the core region and a very small core area, and the wavelength of zero chromatic dispersion was shifted up to 1550 nm to coincide with the lowest losses in the fiber. Therefore, G.653 fiber is also called dispersion-shifted fiber (DSF). G.653 has a reduced core size, which is optimized for long-haul single-mode transmission systems using erbium-doped fiber amplifiers (EDFA). However, its high power concentration in the fiber core may generate nonlinear effects. One of the most troublesome, four-wave mixing (FWM), occurs in a Dense Wavelength Division Multiplexed (CWDM) system with zero chromatic dispersion, causing unacceptable crosstalk and interference between channels.



The G.654 specifications entitled “characteristics of a cut-off shifted single-mode optical fiber and cable”. It uses a larger core size made from pure silica to achieve the same long-haul performance with low attenuation in the 1550nm band. It usually also has high chromatic dispersion at 1550 nm, but is not designed to operate at 1310 nm at all. G.654 fiber can handle higher power levels between 1500 nm and 1600 nm, which is mainly designed for extended long-haul undersea applications.


G.655 is known as non-zero dispersion-shifted fiber (NZDSF). It has a small, controlled amount of chromatic dispersion in the C-band (1530-1560 nm), where amplifiers work best, and has a larger core area than G.653 fiber. NZDSF fiber overcomes problems associated with four-wave mixing and other nonlinear effects by moving the zero-dispersion wavelength outside the 1550nm operating window. There are two types of NZDSF, known as (-D)NZDSF and (+D)NZDSF. They have respectively a negative and positive slope versus wavelength. Following picture depicts the dispersion properties of the four main single-mode fiber types. The typical chromatic dispersion of a G.652 compliant fiber is 17ps/nm/km. G.655 fibers were mainly used to support long-haul systems that use DWDM transmission.



As well as fibers that work well across a range of wavelengths, some are designed to work best at specific wavelengths. This is the G.656, which is also called Medium Dispersion Fiber (MDF). It is designed for local access and long haul fiber that performs well at 1460 nm and 1625 nm. This kind of fiber was developed to support long-haul systems that use CWDM and DWDM transmission over the specified wavelength range. And at the same time, it allows the easier deployment of CWDM in metropolitan areas, and increases the capacity of fiber in DWDM systems.


G.657 optical fibers are intended to be compatible with the G.652 optical fibers but have differing bend sensitivity performance. It is designed to allow fibers to bend, without affecting performance. This is achieved through an optical trench that reflects stray light back into the core, rather than it being lost in the cladding, enabling greater bending of the fiber. As we all know, in cable TV and FTTH industries, it is hard to control bend radius in the field. G.657 is the latest standard for FTTH applications, and, along with G.652 is the most commonly used in last drop fiber networks.


There are different types of single-mode fiber used for different application. G.657 and G.652 are typically favored by planners and installers, and G.657 is particularly deployed for FTTH applications because of a larger bend radius. And G.655 has been taken the place of G.643 used for WDM system. In addition, G.654 is usually applied to the subsea area. To know more information about single-mode fiber, you are welcome to visit the website at FS.COM.

Comparison Between MMF and SMF Optical Cables

According to different standards, fiber optic cables can be categorized into different classifications. One way is to classify the cable into single-mode fiber (SMF) and multimode fiber (MMF). The comparison between these two types of optical cables can assist you in choosing the most suitable cable for device. This article will compare the two kinds of cables from cable path, distance, precision termination, cost and color. Hope you can find some useful information from the article.

Single Path Vs. Multiple Paths

SMF uses laser light which usually follows a single path through the fiber. MMF takes multiple paths, which may result in a differential mode delay. Each type of fiber can be applied for different equipment. It’s important to know which application is more suitable for practical use. Otherwise, it will not operate at optimal levels.


Short Distances Vs. Long Distances

SMF is used for long distance communication, and MMF is used for distances of 500m or less. Each type is equally as effective when chosen for the proper communication device. Make sure to check the ratings to determine which type is best for your application. The distances should be clearly marked.

Thick Core Size Vs. Thin Core Size

SMF typically has a smaller core size of 8.3 to 10 microns in diameter which is more precise for signal transmission in long distance, while the core size of MMF is much larger than SMF from 50 to100 microns in diameter which is more suitable for short distance transmission owing to the signal distortion. With a thinner core size, SMF is only allowed to carry a single light-wave along a single path, while the thick core size makes MMF able to carry different light-waves along numerous paths without modal dispersion limitation.


Low Cost Vs. High Cost

MMF is typically a lower cost solution than SMF. Limited budget may prompt designers to seek solutions with MMF fiber optic cables. The equipment that’s used for communications over MMF is usually less expensive than SMF. But the typical transmission speed and distance of MMF have limitations of 100 Mbit/s for distances up to 2 km.

Color Differences

MMF and SMF cables can also be distinguished by color. Usually, yellow is used for SMF cable color and orange or aqua is used for MMF cables. It is much easier to distinguish them just by their appearance color.


Other Primary Differences

MMF is typically characterized by having a larger core diameter. In most cases, it’s larger than the wavelength of light it supports. Therefore, MMF has more capacity to gather light than SMF. A larger core size means that designers can create a lower cost electronic device and offer a lower price to the public. Also, by using light-emitting diodes (LEDs) and vertical-cavity surface-emitting lasers (VCSELs), the costs can be driven down even more.


SMF and MMF are two different optic cables which have their own separate application fields. It is terribly wrong for not selecting suitable SMF or MMF patch cables according to the application. Think twice before you are certain that the cable is the best choice for your project. If you want to know more details about SMF and MMF fiber optic cables, FS.COM can solve all your problems.

Introduction to LC/MU One-Click Cleaner

When the transmission of the light signal in optic fiber is affected or completely blocked, the main cause is sometimes to be the contamination on the end-faces of connectors or adapters. Therefore, it is extremely important to clean the pollution otherwise the transmission will be greatly influenced. But how can we make a quick and easy clean? The good news is that the problem can now be solved with only one click. The product of one-click cleaner is designed for the convenient and environmental cleaning of end-face contamination, such as road dust, skin oil residue, salt water residue, alcohol residue, vegetable residue, graphite dryer lint, hand lotion and distilled water residue.


The LC/MU one-click cleaner is only available for 1.25mm ferrules, since it is the parameter standard for LC and MU products. Also, the cleaner should be discarded after 800 cleaning times to avoid further contamination. And the LC/MU one-click cleaner can be applied in two polish types of connectors as APC (Angle Polish Connector) and UPC (Ultra Polish Connector).

As for the structure of cleaner, it can be divided into the cover guide cap, guide cap, cleaning tip and a body part. Cover guide cap protects cleaner from dust; guide cap is used for connector cleaning; cleaning tip can be extended for adapter cleaning; cleaner body is used for adjusting the position of tip as standard position or extended position.


The usage of LC/MU one-click cleaner is relatively simple for average people. When it is employed for LC/MU connectors, make sure just remove the cover guide cap. Next, connectors should be inserted into guide cap for a clean click. However, when it is applied for LC/MU adapters, the guide cap should also be removed. Then insert the cleaner tip into adapters with a click. In addition, please pay attention to the depth of adapters. If they are recessed adapters, the tip length should be extended to reach the adapter.


Of course, LC/MU one-click cleaner is just a small category of the one-click cleaner family. According to different types of connectors or adapters, there are also many diverse one-click cleaners, for example, the MTP/MPO one-click cleaner which includes the thumb wheels, the SC/ST/FC one-click cleaner which is used for 2.5mm ferrules and so on. Therefore, people should be careful about the product model before purchasing.

Besides, some fiber optic testers may provide help for the inspection before cleaning and maintenance after cleaning of connectors and adapters. For instance, optical power meter and visual fault locator can be used for detecting whether the light has power loss or is disconnected at a certain point so as to find the specific cleaning area, and the fiber identifier can be employed for the daily maintenance by checking whether the signal is transmitted uninterruptedly after cleaning.

As an easier tool for the cleaning of LC/MU connector and adapter, one-click cleaner is the top choice for everyone who is in charge of the cleaning in data center. With just one click, most of the contamination will be gone, and optic transmission will go back to normal again. For more information about LC/MU one-click cleaner, please visit our website at FS.COM.

What Can Limit the Data Transmission Distance?

In the optical network, except the speed, data transmission distance is another important thing that we care. What can limit the transmission distance? At first we may think of fiber optic cable. Compared with copper cable, it can support longer transmission distance, high speed, high bandwidth, etc. However, not everything is perfect. Fiber optic cable still has some imperfections that influence the transmission distance. Besides, other transmitting media like transceivers, splices and connectors can also limit the transmission distance. The following will tell more details.

Fiber Optic Cable Type

Fiber optic cable can be divided into single-mode cable and multimode cable. The transmission distance supported by single-mode cable is longer than multimode cable. That’s because of the dispersion. Usually the transmission distance is influenced by dispersion. Dispersion includes chromatic dispersion and modal dispersion (as shown in the following figures). Chromatic dispersion is the the spreading of the signal over time resulting from the different speeds of light rays. Modal dispersion is the spreading of the signal over time resulting from the different propagation mode.



For single-mode fiber cable, it is chromatic dispersion that affects the transmission distance. This is because, the core of the single-mode fiber optic is much smaller than that of multimode fiber. So the transmission distance is longer than multimode fiber cable. For multimode fiber cable, modal dispersion is the main cause. Because of the fiber imperfections, these optical signals cannot arrive simultaneously and there is a delay between the fastest and the slowest modes, which causes the dispersion and limits the performance of multimode fiber cable.

Optic Transceiver Module

Like most of the terminals, fiber optic transceiver modules are electronic based. Transceiver modules play the role of EOE conversions (electrics-optics-electrics). The conversion of signals is largely depend on an LED (light emitting diode) or a laser diode inside the transceiver, which is the light source of fiber optic transceiver. The light source can also affect the transmission distance of a fiber optic link.

LED diode based transceivers can only support short distances and low data rate transmission. Thus, they cannot satisfy the increasing demand for higher data rate and longer transmission distance. For longer transmission distance and higher data rate, laser diode is used in most of the modern transceivers. The most commonly used laser sources in transceivers are Fabry Perot (FP) laser, Distributed Feedback (DFB) laser and Vertical-Cavity Surface-Emitting (VCSEL) laser. The following chart shows the main characteristics of these light sources.

Light Source Transmission Distance Transmission Speed Transmission Frequency Cost
LED Short Range


Low Speed Wide Spectral width Low Cost
FP Medium Range High Speed Medium Spectral Width Moderate Cost
DFB Long Range Very High Speed Narrow Spectral Width High Cost
VCSEL Medium Range High Speed Narrow Spectral Width Low Cost
Transmission Frequency

As the above chart mentioned, different laser sources support different frequencies. The maximum distance a fiber optic transmission system can support is affected by the frequency at which the fiber optic signal will be transmitted. Generally the higher the frequency, the longer distance the optical system can support. Thus, choosing the right frequency to transmit optical signals is necessary. Generally, multimode fiber system uses frequencies of 850 nm and 1300 nm, and 1300nm and 1550 nm are standard for single-mode system.


Bandwidth is another important factor that influences the transmission distance. Usually, as the bandwidth increases, the transmission distance decreases proportionally. For instance, a fiber that can support 500 MHz bandwidth at a distance of one kilometer will only be able to support 250 MHz at 2 kilometers and 100 MHz at 5 kilometers. Due to the way in which light passes through them, single-mode fiber has an inherently higher bandwidth than multimode fiber.

Splice and Connector

Splice and connector are also the transmission distance decreasing reasons. Signal loss appears when optical signal passes through each splice or connector. The amount of the loss depends on the types, quality and number of connectors and splices.

All in all, the above content introduces so many factors limiting the transmission distance, like fiber optic cable type, transceiver module’s light source, transmission frequency, bandwidth, splice and connector. As to these factors, different methods and choices can be taken to increase the transmission distance. Meanwhile, equipment like repeater and optical amplifiers are also useful to support the long distance transmission. So there must be some ways to help you increase the transmission distance.

What Should You Know Before Choosing the Single-mode Fiber?

Fiber optical cable has single-mode and multimode type. Multimode fiber includes types of OM1, OM2, OM3, 0M4. How many kinds of single-mode fiber? There are two primary specifications of single-mode fiber. One is the ITU-T G.65x series, and the other is IEC 60793-2-50 (published as BS EN 60793-2-50). This article will introduce ITU-T G.65x series.

single-mode fiber

There are 19 types of single-mode fiber specifications defined by ITU-T (shown in the following table). Different type has different application area. From the change of single-mode fiber specifications, we can see the evolution of transmission system technology. As so many kinds of single-mode fiber, which one should you choose to get perfect performance with the fewest cost? Following will tell about each specifications in details.

ITU-T Specifications Type
ITU-T G.652 ITU-T G.652.A, ITU-T G.652.B, ITU-T G.652.C, ITU-T G.652.D
ITU-T G.653 ITU-T G.653.A, ITU-T G.653.B
ITU-T G.654 ITU-T G.654.A, ITU-T G.654.B, ITU-T G.654.C
ITU-T G.655 ITU-T G.655.A, ITU-T G.655.B, ITU-T G.655.C, ITU-T G.655.D, ITU-T G.655.E
ITU-T G.656 ITU-T G.656
ITU-T G.657 ITU-T G.657.A, ITU-T G.657.B, ITU-T G.657.C, ITU-T G.657.D

ITU-T G.652

ITU-T G.652 fiber is also known as standard SMF (single-mode fiber) and is the most commonly deployed fiber. It comes in four variants (A, B, C, D). A and B have a water peak. C and D eliminate the water peak for full spectrum operation. G.652.A and G.652.B fibers are designed with a zero-dispersion wavelength near 1310 nm, which can be optimized for the operation in 1310nm band. They can also operate in 1550nm band, but it is not optimized for this region due to the high dispersion. The two fibers are usually used within LAN, MAN and access network systems. While G.652.C and G.652.D reduce water peak and can be used in the wavelength region between 1310 nm and 1550 nm supporting Coarse Wavelength Division Multiplexed (CWDM) transmission.

ITU-T G.653

ITU-T G.653 fiber uses a more complex structure in the core region and a very small core area, and the wavelength of zero chromatic dispersion was shifted up to 1550 nm to coincide with the lowest loss in the fiber. It can address this conflict between best bandwidth at one wavelength and lowest loss at another. So G.653 fiber is also called dispersion-shifted fiber (DSF). It has a smaller core size, which is optimized for long-haul transmission system combined with erbium-doped fiber amplifiers (EDFA). However, its high power concentration in the fiber core may generate nonlinear effects. What’s more, four-wave mixing (FWM) occurs in a Dense Wavelength Division Multiplexed (CWDM) system with zero chromatic dispersion, causing unacceptable crosstalk and interference between channels.

ITU-T G.654

G.654 is called “characteristics of a cut-off shifted single-mode optical fiber and cable”. It uses a larger core size made from pure silica to achieve the same long-haul performance with low attenuation in the 1550nm band. It has high chromatic dispersion at 1550 nm but can’t operate at high chromatic dispersion of 1310 nm. G.654 fiber can handle higher power levels between 1500 nm and 1600 nm, which is mainly designed for extended long-haul undersea applications.

ITU-T G.655

G.655 is known as non-zero dispersion-shifted fiber (NZDSF). It has a small, controlled amount of chromatic dispersion in the C-band (1530-1560 nm), where amplifiers work best, and has a larger core area than G.653 fiber. NZDSF fiber can deal with four-wave mixing and other nonlinear effects by moving the zero-dispersion wavelength outside the 1550-nm operating window. There are two types of NZDSF, known as (-D)NZDSF and (+D)NZDSF. Each one has a negative and positive slope versus wavelength. G.655 fibers are mainly used to support long-haul transmission in DWDM system.

ITU-T G.656

G.656 fiber is called Medium Dispersion Fiber (MDF). It’s designed for local access and long haul fiber that performs well at 1460 nm and 1625 nm. This kind for fiber can support long-haul systems that use CWDM and DWDM transmission over the specified wavelength range. And at the same time, it allows the easier deployment of CWDM in metropolitan areas, and increase the capacity of fiber in DWDM systems.

ITU-T G.657
G.657 fiber was originally designed to be compatible with the G.652 fibers but have different bend sensitivity performance. It allows fibers to bend without affecting performance. This is achieved through an optical trench that reflects stray light back into the core and avoids the light lost in the cladding. In reality, it’s hard to control bend radius in the field, such as FTTH applications. G.657 is the latest standard for FTTH applications, and, along with G.652 is the most commonly used in last drop fiber networks.


From the above, different kinds of single-mode fibers have different applications. G.643 is not often used in WDM system because of some problems and is replaced by G.655. G654 is mainly for submarine use. G656 is designed for specific wavelengths. G.657 is compatible with the G.652 but has a larger bend radius than G.652, which is especially suitable for FTTH applications. Now a better understanding of these single-mode fibers will help you to choose the most suitable single-mode fiber.

An Alternative Reading of Fiber Optic Connector

Being a part of the fiber patch cable, the fiber optic connector is utilized to achieve accurate and precise connections of the fiber ends. Now there are many kinds of fiber optic connectors in the market, such as ST, FC, SC, LC and so on (as shown in the following figure). Since the fiber cable transmits pulses of light instead of electrical signals, it is important to choose a good fiber optic connector that aligns microscopic glass fibers perfectly in order to allow for communication. This post will introduce fiber optic connector in an alternative way.

Structure of Fiber Optic Connector

Though the mechanical design varies a lot among different connector types, the most common elements in a fiber connector can be similar. That’s to say, the connector is mainly composed of fiber ferrule, connector sub-assembly body, connector housing, fiber cable and stress relief boot. The following figure takes SC connector as example to show the general components of the connectors.

SC connector
Typical Types of Fiber Optic Connector

Different kinds of optical fiber cables may need different connectors. Seen from the types of optical fiber, the fiber optic connectors may be loosely classified into standard fiber optic connectors, small form factor fiber optic connectors and ribbon fiber connectors. These family types of fiber connectors sometimes may overlap with each other.

Standard Fiber Optic Connectors

Generally having a ferrule of 2.5mm, standard fiber optic connectors are connectors commonly used in the fiber network. They can be both simplex and duplex and available in single mode and multi-mode fibers. ST, FC, SC, FDDI and ESCON are all standard fiber connectors. But they also differ from each other. ST connector is the most popular connector for multi-mode fiber optic LAN applications. FC connector is specifically designed for telecommunication applications and provides non-optical disconnect performance. SC connector is widely used in single mode applications for its excellent performance. FDDI connector, which is a duplex multi-mode connector, utilizes two 2.5mm ferrules and is designed to used in FDDI network. ESCON connectors are similar to FDDI connectors, but contain a retractable shroud instead of a fixed shroud.

Small Form Factor Fiber Optic Connectors

To meet the demand for devices that can fit into tight spaces and allow denser packing of connections, a number of small form factor fiber optic connectors have been developed since the 1990s. In this type of small form factor fiber optic connectors, some are miniaturized versions of older connectors, built around a 1.25mm ferrule rather than the 2.5mm ferrule. For example, the LC, MU, E2000 connectors. While the others are based on smaller versions of MT-type ferrule for multi-mode fiber connections, or other brand new designs. For example, the MT-RJ connector, which has a miniature two-fiber ferrule with two guide pins parallel to the fibers on the outside. Its overall size is about the same as a RJ45 connector.

Ribbon Fiber Connectors

MTP and MPO are compatible ribbon fiber connectors based on MT ferrules which allow quick and reliable connections for up to 12 fibers. Since the MTP product complies with the MPO standard, the MTP connector is an MPO connector. Along with the MTP patch cables (for example, MTP-MTP fiber trunk cable), MTP connectors can upgrade the 10G network to 40G/100G.


The fiber optic connector is an essential part in fiber optical network. As the popularity of fiber optical network, about 100 fiber optic connectors have been introduced to the market. FS.COM is the main professional fiber optic products supplier in China, and we offers various kinds of fiber cable connectors, especially the commonly used FC, LC, SC, ST and MPO connectors.

MTP/MPO Cables—An Ideal Solution for High-Density Cabling

For various reasons, the data quantity transmitted worldwide is growing exponentially and the need for ever-greater bandwidths continues unabated. Though the current data volumes demanded in backbone cabling can still be handled with 10 GbE, the forecast trends will require the introduction of the next technologies, 40 GbE and 100 GbE (Figure 1). Therefore, data centers must respond early to provide sufficient capacities and plan for upcoming requirements. To meet this demand, 40G QSFP+ transceivers, MTP/MPO cables and other related products are springing up like mushrooms in the market. They are important roles in the ultra-high density cabling in data centers. This post will focus on MTP/MPO cables in the data center.

trend over time of Ethernet technologies
Why MTP/MPO Cables Are Used?

For the reasons mentioned above, the number of network connections in data centers is on the rise rapidly. And the use of traditional fiber cables may make the data center crowed and difficult to be managed. To solve this problem, data centers have to achieve ultra-high density in cabling to accommodate all this cabling in the first place. The MTP/MPO cables, which bring together 12 or 24 fibers in a single interface (Figure 2), have been proven to be a practical solution. Incorporating to meet the 40GBASE-SR4 and 100GBASE-SR10 standard, The MTP/MPO multi-fiber connector of MTP/MPO cables is about the same size as a SC connector but can accommodate 12 or 24 fibers. Thus, MTP/MPO cables provide up to 12 or 24 times the density and offer savings in circuit card and rack space.

MPOMTP multi-fiber connectors
Details of MTP/MPO Cables

MTP/MPO cables are composed of MTP/MPO connectors and fiber cables, other connectors such as LC may also be found in some kinds of MTP/MPO cables. And the fiber cables used are generally OM3 and OM4, which are laser optimized multi-mode optical fibers. Unlike traditional connectors, the MTP/MPO connector should be carefully used to ensure proper connections are made. Thus, it is important to have an overall understanding of MTP/MPO connectors.

As is shown in the following figure, each MTP/MPO connector has a key on one side of the connector body, and the key sitting on top referred to as the key up position. In this orientation, each of the fiber holes in the connector is numbered in sequence from left to right. People often refer to these connector holes as positions, or P1, P2, etc. In addition, there is a white dot on the connector body to designate the P1 side of the connector when it is plug in.

MPO connector

There are two types of MTP/MPO adapters based on the placement of the key: key up to key down and key up to key up. When you want to connect two MTP/MPO connectors, it is important to choose a right adapter with keying designed to hold the two facing ends of the MTPs incorrect alignment. The following figure shows the right connections of two MTP/MPO connectors within the adapter.

MPOMTP connectors held within the adaptor
Common Types of MTP/MPO Cables

MTP/MPO trunk cable and MTP/MPO harness cable are two common kinds of MTP/MPO cables. MTP/MPO trunk cables serve as a permanent link connecting the MTP/MPO modules to each other. And they can offer flexibility in changing the connector style in the patch panels. MTP/MPO harness cables provide a transition from multi-fiber cables to individual fibers or duplex connectors. These cables are offered for various applications for all networking and device needs like 100G modules including CFP, CFP2 and CFP4 series.


There is no way around the migration to 40 and 100 GbE. As the figure shows above, 40 and 100 GbE will be broadly introduced in the near future. Therefore, Data center managers will have to lay the groundwork today and adapt their infrastructure to meet future requirements. MTP/MPO cables are inevitable the ideal solution to meet these needs. Fiberstore is now striving to be a leading supplier of MTP/MPO connection components. We manufacture and distribute a wide range of MTP/MPO connection components including the MTP/MPO connectors, adapters, cables, cassettes, adapter panels, loopback modules, etc.

A Copper-based Gigabit Ethernet Solution – 1000BASE-T

Enormous efforts put on the development of high-performance Ethernet technology that provides gigabit-per-second transmission rates have led to the extension of Gigabit products to include the copper Gigabit Ethernet (GbE) standard: 1000BASE-T. Many papers and articles have been attributed to introducing the fiber-optic GbE standards, such as 1000BASE-SX, 1000BASE-LX, 1000BASE-ZX. And contributions are few about 1000BASE-T. This text just helps you to better understand 1000BASE-T and talks about it: a copper GbE solution.

What Is 1000BASE-T Technology?

1000BASE-T is also known as IEEE 802.3ab. Just judging from its name, “1000” here means the transmission speed of 1000Mbps. The “BASE” refers to BASE band signaling, indicating that only Ethernet signals are carried on the medium. The “T” represents twisted-pair copper cable (for example Cat 5). More specifically, 1000BASE-T uses four pairs of Cat 5 unshielded twisted pair (UTP) to achieve the Gigabit data rate and achieves 1000Mbps data rates by sending and receiving a 250Mbps data stream over each of the four pairs simultaneously. The distribution of four-pair Cat 5 cabling extends from the work area to the equipment room and between equipment in the equipment room, thus enabling connectivity to switched and shared gigabit services for both high-bandwidth work area computing and server farms.

four cat 5 UTP pairs

1000BASE-T is able to provide half-duplex (CSMA/CD) and full-duplex 1000Mb/s Ethernet service over Cat 5 links as defined by ANSI/TIA/EIA-568-A. Besides GbE applications over Cat 5 copper cabling, 1000BASE-T also supports other specifications. First, it supports the Ethernet MAC (Media Access Control), and is backward compatible with a 10/100 Mbps Ethernet. Second, many 1000BASE-T products support 100/1000 auto-negotiation, and therefore 1000BASE-T can be incrementally deployed in a Fast Ethernet network. Third, 1000BASE-T is a high-performing technology with less than one erroneous bit in 10 billion transmitted bits. (10 is the same error rate as that of 100BASE-T.) Topology rules for 1000BASE-T are the same as those used for 100BASE-T.

Why Choose This Copper Gigabit Ethernet Solution?

Why network designers choose 1000BASE-T as the copper GbE solutions? Or put it in another way, what are the advantages of 1000BASE-T?

  • Performance—1000BASE-T scales Ethernet 10/100Mbps performance to 1000Mbps. Compared with 1Gbps, 1000BASE-T is 100 times as fast as the standard Ethernet. It permits the smooth migration of the 10/100 networks to 1000 Mbps-based networks. When 1000BASE-T technology is deployed in transceiver modules, these 1000BASE-T SFP transceivers, such as Fiberstore compatible Cisco SFP-GE-T, make shared gigabit service possible and aggregate one gigabit of server support. This Cisco 1000BASE-T SFP supports 1000BASE-T operation in host systems with a compact RJ-45 connector assembly.

SFP-GE-T, Cisco 1000BASE-T SFP

  • Cost—Used in conjunction with Full Duplex Repeaters (FDRs), 1000BASE-T can provide highly cost-effective shared gigabit service. FDRs offer the traditional low-cost shared media operation of repeaters, but when coupled with 1000BASE-T, they offer an easy-to-manage, high-burst rate, shared-media solution capable of supporting both end users and server farms. In such a case, to aggregate one gigabit of server support is possible in a cost-effective way.
Notes on Using 1000BASE-T Products

While realizing a 1000Mb/s data stream over four pairs of Category 5 twisted pair cables meet several challenges may meet several challenges, like signal attenuation, echo, return loss, etc.

  • Attenuation is the signal loss of the cabling from the transmitter to the receiver. Attenuation increases with frequency, so designers are challenged to use the lowest possible frequency range that is consistent with the required data rate.
  • Echo is a by-product of dual-duplex operation, where both the transmit and receive signal occupy the same wire pair. The residual transmitted signal because of the trans-hybrid loss combines with the cabling return loss to produce an unwanted signal referred to here as echo.
  • Return loss is a measure of the amount of power reflected due to cabling impedance mismatches.

1000BASE-T technology is the ideal high-speed solution for these application when 1000BASE-T uplinks from desktop switches to aggregating switches. Many network designers have chosen this copper GbE solution for high network performance in a cost-effective way. Fiberstore supplies many 1000BASE-T SFPs which are fully compatible with major brands, like Cisco GLC-T and SFP-GE-T mentioned above. For more information about 1000BASE-T SFPs, you can visit Fiberstore.

Considering Three Aspects Before Migrating to 40G

The dramatic growth of bandwidth requirements in data centers has led to the worldwide use of higher-performance optical products for network scalability, management, flexibility and reliability. Currently, 10GbE (Gigabit Ethernet) can’t meet the increasing needs of high speed transmission well for such applications as Big Data, cloud and Internet of Things being introduced in many industries. As such, network migration to 40/100G has already been the industry consensus.

But as the cost for 100G is far beyond what most enterprises can afford and the technology for 100G is still not mature enough, 40G has been a better solution for its lower cost and maturer technologies compared to 100G. Nowadays, some manufacturers are battling for the 40G market, which drives down the 40G deployment price, leading to the even wider deployment of 40G infrastructure. When migrating from 10G to 40G, three aspects should be considered: fiber optic transceiver, transmission media, and pre-terminated MPO assemblies.

Fiber Optic Transceiver

For any telecommunication network, fiber optic interconnection is of great importance. Photoelectric conversion is a necessary part in fiber optic network. The function of fiber optic transceiver is photoelectric conversion, which makes it one of the most commonly used components in the data center.

As for 40G transceivers, two different package forms are available: QSFP+ (Quad Small Form-factor Pluggable Plus) and CFP (C Form-factor Pluggable), with the former more widely-used than the latter. A single 40G fiber optic transceiver may not be expensive. But what a medium-sized data center needs is thousands of optical transceivers, meaning a large sum of money to be spent. In such a case, third party transceivers that are compatible with a variety types of switches come into point. They have the same performances that the original brand transceivers have, but cost less money. When selecting 40G compatible transceivers, cost and quality are very important. Choosing the compatible 40G transceivers from Fiberstore can ensure 100% compatibility and interoperability. The picture below shows the testing of Cisco compatible QSFP-40G-SR4 transceivers on a Cisco switch to ensure its compatibility and interoperability.

QSFP-40G-SR4, under test

Transmission Media

Allowing for several situations that may exist, the IEEE 802.3ba specified the different transmission media for 40G links, including the following listed media:

  • 40GBASE-CR4: 40Gb/s Ethernet over copper cable in short transmission distance.
  • 40GBASE-SR4 (eg. QFX-QSFP-40G-SR4): 40Gb/s Ethernet over four short-range multi-mode fiber (MMF) optic cables.
  • 40GBASE-LR4: 40Gb/s Ethernet over four wavelengths carried by a signal long-distance single-mode fiber (SMF) optic cable.

There also exists hybrid cabling solutions for 40G applications, like QSFP to 4SFP+ breakout cabling assembly. Take QSFP-4SFP10G-CU5M for example, this product listed in Fiberstore is the QSFP+ to 4 10GBASE-CU SFP+ passive direct-attach copper transceiver assembly with 5-meter reach.

QSFP to 4SFP+ breakout cabling assembly, for short reach, 5m

Question occurs: fiber optic cable or copper cable, which should be used in 40G migration? Copper is cheaper. But it can only support 40G transmission limited to several meters. SMF supports the longest 40G transmission distance up to 40 km. As for MMF, OM3 and OM4 are suggested to support short distance transmission. The longest distance that OM3 can support for 40G transmission is 100 m. OM4 can support a longest 40G transmission distance of 150 m. The selection of transmission media should depend on the specific applications.

MPO Assemblies for 40G

The IEEE 802.3ba standard also specifies multi-fiber push-on (MPO) connectors for standard-length MMF connectivity. Most of the 40G multi-mode Ethernet transceivers are based on the MPO technology. It is wise to increase fiber optic density by using MPO technology, but a new problem arises. As the fiber number increased, the cabling and splicing difficulty in data center increased. Unlike traditional two-strand fiber connections, MPO connectors cannot be field terminated easily. Thus, most of the data centers choose the pre-terminated MPO assemblies in 40G deployment, which is more reliable and can save more human labor. Before cabling, determine the cabling lengths and customized pre-terminated MPO assemblies with manufacturers would save a lot of time and money.


Using compatible third party transceivers of high quality for 40G links saves a lot of money. Taking specific applications and characteristics of 40G transmission media into consideration can also help you to save cost. Pre-terminated MPO assemblies are necessary for flexible and manageable cabling in 40G deployment. With these information in mind, cost-effective 40G migration is at the corner.

In-depth Understanding of Fiber Optic Cables

The commitment to fiber optic technology has spanned more than 30 years, and nowadays a high level of glass purity, fiber optic cable, has been achieved owing to the continuous research and development. This purity, combined with improved system electronics, enables to transmit digitized light signals over hundreds of kilometers with high performance, offering many advantages in fiber optic systems. This text provides an overview of the construction, categories, and working principles of this fiber optic cable.

Construction of Fiber Optic Cable

Fiber optic cable generally consists of fiver elements : the optic core, optic cladding, a buffer material, a strength material and the outer jacket. Here, much more detailed information is attributive to the optic core and optic cladding which are both made from doped silica (glass).

The Optic Core and Cladding Details

The optic core is the light-carrying element at the center of the cable, and the optic cladding surrounds the optic core. Their combination makes the principle of total internal reflection possible. Besides, a protective acrylate coating then surrounds the cladding. In most cases, the protective coating is a dual layer composition: a soft inner layer that cushions the fiber and allows the coating to be stripped from the glass mechanically, and a harder outer layer that protects the fiber during handling, particularly the cabling, installation, and termination processes. This coating protects the glass from dust and scratches that can affect fiber strength.

Optic Core and Cladding, makes reflection possible

Categories of Fiber Optic Cable

There are two general categories of fiber optic cable: single-mode fiber (SMF) and multi-mode fiber (MMF).

MMF was the first type of fiber to be commercialized. It has a core of 50 to 62.5 µm in diameter much larger than SMF, allowing hundreds of modes of light to propagate through the fiber simultaneously. Additionally, the larger core diameter of MMF facilitates the use of lower-cost optical transmitters (such as light emitting diodes or vertical cavity surface emitting lasers) and connectors, more suitable for relatively shorter-reach application. Take 1 Gigabit Ethernet (GbE) applications for example, MMF is deployed to establish 550m link length with 1000BASE-SX SFPs (eg. Cisco Meraki MA-SFP-1GB-SX).

SMF, in contrast, has a much smaller core, approximately 8 to 10 µm in diameter, which allows only one mode of light at a time to propagate through the core. It’s designed to maintain spatial and spectral integrity of each optical signal over longer distances, permitting more information to be transmitted. Similarly, as for 1GbE applications, SMF is able to realize 70km reach with 1000BASE-ZX SFPs, like GLC-ZX-SM, a product compatible with Cisco listed in Fiberstore.


Working Principles of Fiber Optic Cable

The operation of a fiber optic cable is based on the principle of total internal reflection. Light reflects (bounces back) or refracts (alters its direction while penetrating a different medium), depending on the angle at which it strikes a surface.

This principle comes at the center of how fiber optic cable works. Controlling the angle at which the lightwaves are transmitted makes it possible to control how efficiently they reach their destination. Lightwaves are guided through the core of the fiber optic cable in much the same way that radio frequency (RF) signals are guided through coaxial cable. The lightwaves are guided to the other end of the fiber being reflected within the core. The composition of the cladding glass related to the core glass determines the fiber’s ability to reflect light. That reflection is usually caused by creating a higher refractive index in the core of the glass instead of in the surrounding cladding glass, creating a waveguide. The refractive index of the core is increased by slightly modifying the composition of the core glass, generally by adding small amounts of a dopant. Alternatively, the waveguide can be created by reducing the refractive index of the cladding using different dopants.


In fiber optic cables, the light can carry more information over longer distances than the amount carried in a copper or coaxial medium or radio frequencies through a wireless medium. With few transmission losses, low interference, and high bandwidth, fiber optic cables are the ideal transmission medium. Fiberstore offers various kinds of fiber optic cables, including SMF and MMF types, simplex and duplex fiber optic cables, indoor distribution cables and outdoor loose tube cables, etc. For more information about fiber optic cables, you can visit Fiberstore.

Overview of 40/100GbE Terminations

Today’s data centers growth is placing increasing demands on the networking infrastructure. For some enterprises, existing 1GbE connections can’t support the growing business requirements well very, not to say 100Mbps connections. In order to accommodate these demands, it’s imperative to upgrade the data center network architecture to 40 or 100 Gigabit Ethernet (GbE) connections. This 40/100GbE network design helps to support not only the current growth, but also the increasing demands in the future.

IEEE 802.3ba 40G and 100G Standard

The Institute of Electrical and Electronics Engineers (IEEE) 802.3 working group is concerned with the maintenance and extension of the Ethernet data communications standard. And 802.3ba is the designation given to the higher speed Ethernet task force to modify the 802.3 standard to support higher speeds than 10Gbit/s, that is 40/100G in 2010. This 802.3ba 40/100G standard encompasses a number of different Ethernet physical layer (PHY) specifications which are supported by means of pluggable modules, like Quad Small-Form-Factor Pluggable (QSFP) and C Form-Factor Pluggable (CFP). As for transmission medium, the transport speeds at 40/100Gbit/s use two methods: parallel optics and copper cables, with the fiber optics solutions allowing more flexibility and greater distance reach.

40GbE Terminations

In most cases, 40GbE connections use a QSFP+ transceiver terminated to receive the multi-fiber push-on/multiplex pass-through (MPO/MPT) trunk. That is, the short-range QSFP+ transceivers (eg. QFX-QSFP-40G-SR4) use multi-mode MPO trunks to establish 40G links. During this link establishment, polarity becomes a consideration when implementing 40GbE switch-to-switch interconnects over multi-strand multi-mode fiber (MMF). Method B polarity is recommended for the functional link.

QSFP+ transceivers are also able to run on single-mode fiber (SMF) for long reach. These links are Little Connector (LC) terminated and can run up to 40km, mainly used for 40GbE interbuilding connections. Take QSFP-40G-ER4 for example, this 40GBASE-ER4 transceiver supports link lengths up to 40km over SMF with duplex LC connectors.

The QSFP+ transceiver can also be used for 40GbE to 4x10GbE partitioned applications, that is QSFP+ to 4SFP+ fan-out cabling assemblies. One end of the connection is terminated using a MPO/MPT configuration with four individual pairs terminated with LC connectors at the other end. The image below just shows the QSFP+ to 4SFP+ Active Optic Cable (AOC) assembly.

QSFP+ to 4SFP+ AOC, 40GbE to 4x10GbE partitioned application

100GbE Terminations

100GbE connections use a CFP transceiver. Two CFP options are dominant in the industry: CFP2 and CFP4. The primary differences between the two are physical density and transmit/receive lane configurations. More specifically, CFP2 supports 100GBASE-SR10, 100BASE-LR4, and 100GBASE-ER4 optical interfaces, while CFP4 doubles the port density on the line card and supports 100GBASE-SR4, 100GBASE-LR4, and 100GBASE-ER4 optical interfaces.

CFP options, for 100G transmission

40/100GbE Termination Benefits

The 40/100GbE network infrastructure provides the following benefits:

  • Reduced data center complexity: As virtualization increases, the use of fewer physical servers and switches has been made possible by 40/100GbE network infrastructure.
  • Reduced total cost: Since 40/100GbE network system simplifies the local area network (LAN) and cable infrastructures, the potential cost reduction in virtualization environment is also accessible. Besides, the 40/100GbE network infrastructure requires fewer data center space, power, and cooling resources.
  • Increased Productivity: Faster connections and reduced network latency provide network designers with faster workload completion times and improved productivity.

Upgrading network architecture to support speeds greater than 10GbE, that is 40/100GbE, is essential in optimizing data center infrastructure, giving a hand in moving quickly in respond to business needs. At the same time, the services and value brought by information technology itself can also be enhanced.


The high-performance 40/100GbE network architecture simplifies the cabling infrastructure and reduces per-server total cost of ownership, capable of allowing high speeds at 40/100Gbit/s. Fiberstore offers a large selection of 40/100G optical modules, as well as 40/100G fiber optic-based cables and copper cables. For more information about 40/100GbE solutions, you can visit Fiberstore.

Single Fiber – Why Choose it for Gigabit Optical Communications?

Advanced applications, including voice and data convergence, as well as storage area networking, are putting burdens on today’s fiber optic networking infrastructure, especially on the fiber cabling. With speeds in data centers now increasing from 10Gbps to 40Gbps, to 100Gbps, and 120Gbps, etc., different fiber technologies are required for Gigabit optical communications, like single strand fiber (simplex fiber cable) and duplex fiber cable. This text mainly introduces the single strand fiber, a relatively simple solution chosen for fiber optimization, and its benefits that drive the need to deploy single strand fiber for Gigabit optical communications.

Single Fiber Technologies

Single strand fiber, just as its name shows, uses one strand of glass instead of two dedicated strands with one for receiving and the other for transmitting. It doubles the capacity of the installed fiber plant, which in turn doubles the per fiber return on investment (ROI) with no need for more physical fiber.

Early single fiber solutions were based on single wavelength directional coupler technologies. With these solutions, the same wavelength (1310nm for up to 50km or 1550nm for longer distances) travels in each direction (transmit & receive). At the edges, the two signals are coupled into a single fiber strand with a directional coupler (splitter-combiner). This coupler identifies the direction of the two signals (ingress or egress) and separates or combines them. This kind of solution is normally very reliable and cost effective, as long as special installation and connector type (APC -angle polished connector) requirements are observed. Otherwise, this solution is prone to reflections when traversing patch panels and in the cases of fiber cuts or dirty connectors.

single fiber 1310nm TX/1510nm Rx

In recent years, a new single strand fiber technology has emerged based on two wavelengths traveling in opposite directions. External WDM couplers (multiplexers) combine or separate the two wavelengths at the edges. As technology progressed, the external passive WDM coupler became integrated into a standard interface fixed optic transceiver.

Single Fiber SFP (Small Form Pluggable)

The growing demand of single fiber solutions driven by the Ethernet bandwidth has led to the development of a wide range of single fiber pluggable SFP transceivers. These hot-pluggable optic transceivers are designed in small-form factor for high-density solutions, covering many industrial protocols and allowing flexibility in distance choices. Besides, they provide advanced optical performance, Digital Diagnostics Monitoring (DDM). Commonly-used single SFPs include 1000BASE-LX SFPs (eg.EX-SFP-1GE-LX shown below), 1000BASE-ZX SFPs, etc.

EX-SFP-1GE-LX,single fiber SFP

Single Fiber Benefits

The benefits of the single strand versus the dual strand fiber implementation can be considerable.

  • Operational and Capital Expense Savings

Single fiber solutions, like any other fiber optimization methods, affect both the capital expenses (CAPEX) and the operational expenses (OPEX). For fiber users like carriers and enterprises that lease dark fiber from their provider rather than owning the fiber plant, the OPEX savings is extremely significant by avoiding avoid the need to install additional fiber strands to accommodate growth without imposing limitations due to engineering capabilities.

  • Fiber Run — Engineering Cost

The design and engineering of a fiber run is a complex process. It may require crossing roads or freeways, which leads to possible thorough design, and inflexible work scheduling. The deployment cost might include trenching or other expenses. In many cases, the price of labor, services, and licenses required to install new cabling can far exceed the cost of the media and supporting electronics.

  • Fiber Termination and Accessories Cost

New fiber runs require terminating and connecting any fiber strand. This process requires qualified labor that will polish, connectorize, and test every fiber strand. Reducing the number of terminated fiber strands by half results in a significant cost reduction.

  • Network Reliability and Maintenance Cost

Reliability and availability are key in any communications system. Use of single fiber pluggable-based transceivers in an existing dual fiber link opens the possibility of creating redundant link solutions. In fiber assembly, a larger number of fiber strands increase the chance of fiber failure. The larger the fiber strands are, the higher the failure chances are, thus the maintenance cost increase accordingly. This can be reduced through the simplicity of single fiber technology.


Single fibers are considered as the simple way for fiber optimization, for they not only double the capacity of the installed fiber plant, but also help to achieve overall savings in Gigabit optical communications. Fiberstore offers single fibers available in both single-mode and multi-mode versions, which are all quality assured. In addition, single fiber optical transceivers can also be found in Fiberstore, such as 1000BASE-LX SFP (EX-SFP-1GE-LX mentioned above), 10GBASE-ZR SFP+ (SFP-10G-ZR). For more information about single fibers, you can visit Fiberstore.

FAQs About Laser-Optimized Fiber

Fiber optical networks have dominated for long-haul communications for years, increasingly used in short distance applications, such as local area networks (LANs). And the Ethernet data-rate needed for these high-performance fiber optic networks increases from 1Gbps to 10Gbps, to 40Gbps, to 100Gbps, or even higher. Together with this speed increase, a term, laser-optimized fiber, has crept into the telecommunication market. What is laser-optimized fiber? How much do you know about it? Knowing answers to these frequently asked questions (FAQs) about laser-optimized fiber will help you prepare for the latest wave in optical communication networks.

FAQ 1: What Is Laser-Optimized Fiber?

Laser-optimized multi-mode fiber (LOMMF: OM3 & OM4) differs from standard MMF (OM1 & OM2), because the former has graded refractive index profile fiber optic cable in each assembly. This means that the refractive index of the core glass decreases toward the outer cladding, so the paths of light towards the outer edge of the fiber travel quicker than the other paths. This increase in speed equalizes the travel time for both short and long light paths, ensuring accurate information transmission and receipt over much greater distances up to 300 meters (OM3) and 400 meters (OM4) at 10Gbps, while OM1 and OM2 can only realize 26 meters and 33 meters link length respectively at the same data rate. And when 1000BASE-SX SFP transceivers transmit and receive signals over LOMMF and standard MMF at 1Gbps, the possible link lengths achieved are also different, with OM1 275-meter reach, OM2, OM3, and OM4 up to 550-meter reach. Take MGBSX1 for example, this compatible Cisco 1000BASE-SX SFP listed in Fiberstore supports up to 550-meter link length over OM2.

MGBSX1, 550m link length over MMF

FAQ 2: Why Have MMF Been “Optimized” for Use with Lasers?

As the demand for bandwidth and higher throughput increased, especially in building and campus backbones, LEDs, short for Light Emitting Diodes, that are used as light sources in fiber optic systems could not keep pace. With a maximum modulation rate of 622Mb/s, LEDs would not support the 1 Gb/s and greater transmission rates required. The use of traditional lasers (Fabry-Perot, Distributed Feedback) typically used over single-mode fiber (SMF) could accommodate this problem. However, it’s very expensive due to the higher performance characteristics required for long-distance transmission on SMF. As such, a high-speed laser light source, a Vertical Cavity Surface Emitting Laser (VCSEL) was developed. These VCSELs are inexpensive, suited for low-cost 850nm multi-mode transmission systems, allowing for data rates up to 100Gbps in the enterprise. With the emergence of these VCSELs, MMFs have been “optimized” for operation with lasers.

FAQ 3: Why Are LOMMFs the Best Choice for Use with VCSELs?

After VCSELs appears, to fully capitalize on the benefits that VCSELs offer, LOMMFs have been specifically designed, fabricated, and tested for efficient and reliable use with VCSELs.

LOMMF,specifically designed, fabricated, and tested

LOMMFs have a well-designed and carefully controlled refractive index profile to ensure optimum light transmission with a VCSEL. Precise control of the refractive index profile minimizes the modal dispersion, also known as Differential Mode Delay (DMD). This ensures that all modes, or light paths in the fiber arrive at the receiver at about the same time, minimizing pulse spreading and, therefore, maximizing bandwidth.

LOMMF is completely compatible with LEDs and other fiber optic applications. LOMMFs can be installed at slower data rates or higher data rate. When there occurs the data rate migration from 10Gbps to 40Gbps, there is no need to pull new cable. You only need to upgrade the optics modules to VCSEL-based transceivers, avoiding infrastructure redesign.


LOMMFs are the suitable medium for short-wave 10G optical transmission. Their great bandwidth- and information-carrying capacity make them more popular among consumers than standard MMFs especially in 10GbE systems. Fiberstore supplies countless OM3 and OM4, as well as OM1 and OM2 for your network projects. Besides, other kinds of fiber optic cables, like MTP cable and SMF, are also available in Fiberstore. For more information about fiber optic cables, please visit Fiberstore.

Pluggable Transceivers Used in Data Centers

Today’s data centers are going through unprecedented growth and innovation as emerging optical standards and customers’ demands for higher-level networking services converge. Bandwidth, port density and low-power demands come as the main drivers that populate the deployment of fiber optic networks. And in fiber optic network implementations, pluggable transceivers provide a modular approach to safe-proof network design and become the ideal choice to meet the ever-changing network needs in data centers. This text just mainly introduces pluggable transceivers deployed in data centers.

A Quick Question: What Are Pluggable Transceivers?

Pluggable transceivers are transceivers that can be plugged into routers, switches, transport gear, or pretty much any network device to transmit and receive signals. They are hot swappable while the device is operating, standardized to be interchangeable among vendors, capable of operating over many different physical medium and at different distances. For instance, pluggable transceivers can work through copper, through fiber optic cables available in both single-mode fibers (SMFs) and multi-mode fibers (MMFs), realizing 100m, 300m, 10km, 80km distance reach, etc. In addition, these hot-swappable transceivers are also able to support a wide variety of speeds, like 1Gbit/s, 10Gbit/s, 40Gbit/s, 100Gbit/s, or even higher.

Pluggable Transceiver – Standards & Protocols

Just as what has been mentioned above, pluggable transceivers are interchangeable. These interchangeable transceivers allow a single device to operate with a wide selection of protocols and functions. Listed below are commonly-used pluggable transceiver standards and protocols.

SFP—The small form-factor pluggable (SFP) supports a wide range of protocols and rates, such as Fast and Gigabit Ethernet (GbE), Fibre Channel (FC), and synchronous optical networking (SONET) for dual and bidirectional transmission. SFP medium are available in SMF, MMF, and copper. For MMF media, there exists 1000BASE-SX port type used in 1GbE applications. Take J4858C for example, this HP 1000BASE-SX SFP can realize a maximum of 550m reach at 1.25 Gbit/s over MMF.

J4858C, HP 1000BASE-SX SFP

SFP+—The enhanced small form-factor pluggable (SFP+) is an enhanced version of the SFP, supporting data rates up to 16Gbit/s. It was first published on May 9, 2006, and version 4.1 was published on July 6, 2009, supporting 8Gbit/s FC, 10GbE and Optical Transport Network standard OTU2. SFP+ is a popular industry format supported by many network component vendors.

XFP—The XFP (10G SFP) is a standard for transceivers for high-speed computer network and telecommunication links that use optical fiber. Its principal applications include 10GbE, 10Gbit/s FC, SONET at OC-192 rates, synchronous optical networking STM-64, 10 Gbit/s Optical Transport Network (OTN) OTU-2, and parallel optics links.

QSFP—The Quad Small Form-factor Pluggable (QSFP) is a also a compact, hot-pluggable transceiver used for data communications applications. QSFP+ transceivers are designed to carry Serial Attached SCSI, 40GbE (100G using QSFP28), QDR (40G) and FDR (56G) Infiniband, and other communications standards. They increase the port-density by 3x-4x compared to SFP+ modules. In 40GbE applications, these QSFP+ transceivers establish 40G links with distances up to 300m over MMF, and 40km over SMF. QSFP can also take copper as its media option when the required distance is short. Like QSFP-4SFP10G-CU5M, this product is the QSFP to 4 10GBASE-CU SFP+ direct attach passive copper cable assembly designed for relatively short reach, that is 5m. The image below just shows what this QSFP-4SFP10G-CU5M product looks like.


CFP—The C form-factor pluggable (CFP) is a multi-source agreement (MSA) to produce a common form-factor for the transmission of high-speed digital signals. The c stands for the Latin letter C used to express the number 100 (centum), since the standard was primarily developed for 100 Gigabit Ethernet systems.


Pluggable transceivers offer distance extension solutions, allowing flexibility in network reach and easy replacement in the event of component failures. They are the answer to today’s network architecture and performance demands. Fiberstore supplies various pluggable transceivers supporting different speeds, like SFP (J4858C), SFP+, XFP, QSFP, CFP, etc. Additionally, their transmission medium available in fiber and copper can also be found in Fiberstore. For more information about pluggable transceivers, you can visit Fiberstore.

Three Media Options for 10GbE in Data Centers

With the added network infrastructure complexity, power demands, and cost considerations, 10 Gigabit Ethernet (GbE) comes to network administrators’ thinking point. While 1GbE connection is able to handle the bandwidth requirements of a single traffic type, 10GbE has been preferred as the ideal solution by customers to meet current and future input/output (I/O) demands. Delivering more bandwidth, 10GbE simplifies the network infrastructure at the same time by consolidating multiple gigabit ports into a single 10gigabit connection.

Generally speaking, there are three media options for 10GbE: 10GBASE-CX4, SFP+, and 10GBASE-T. Each option has its own virtual point and downside in terms of cost, power consumption and distance reach. This paper analyzes these three options respectively, helping you understanding the pros and cons of current 10GbE media options.


10GBASE-CX4 was the first 10G copper standard published by 802.3 (as 802.3ak-2004), an early favorite standard for 10GbE deployments. Using the XAUI 4-lane PCS (Clause 48) and copper cabling similar to that used by InfiniBand technology, 10GBASE-CX4 is able to reach 15 meters. Practically, this option is limited by its heavy weight and expensive cables. In addition, the size of the CX4 connector prohibited higher switch densities required for large scale deployment. Larger diameter cables are purchased in fixed lengths, causing problems in managing cable slack. What’s more, the space isn’t sufficient to handle the larger cables.


SFP+ fiber optic cables and SFP+ direct attach cables (DACs) are all better solution than CX4.

10GBASE SFP+ Fiber Optic Cables

10GBASE-SR, 10GBASE-LR, 10GBASE-LRM are all specified to work through fiber optic cables, such as JD094B (shown below). This HP 10GBASE-LR SFP+ transceivers takes fiber as its transmission medium with distance up to 10km. Really, great for latency and distance, but fibers are expensive. Although they offer low power consumption, the project of laying fiber networks in data centers is limited due to the cost of the electronics largely. The fiber electronics can be four to five times more expensive than their copper counterparts, meaning that ongoing active maintenance, typically based on original equipment purchase price, is also more expensive.

JD094B, HP 10GBASE-LR SFP+ transceiver


DAC can be classified in to direct attach copper cable and active optic cable (AOC). On the one hand, SFP+ DAC is a lower cost option alternative to fiber, with its distance reaching flexible in 1m (eg. SFP-10G-AOC1M), 2m, 3m, 5m, 7m and so on. On the other, SFP+ DAC is not backward-compatible with existing 1GbE switches. Besides, this solution requires the purchase of an adapter card and requires a new top of rack (ToR) switch topology. And the cables are much more expensive than structured copper channels, and cannot be field terminated. All these factors make SFP+ DAC less popular the 10GBASE-T which will be discussed soon.SFP-10G-AOC1M, for short reach


10GBASE-T, or IEEE 802.3an-2006, is a standard released in 2006 to provide 10Gbit/s connections over unshielded or shielded twisted pair cables with distances up to 100metres (330 ft). Due to additional encoding overhead, 10GBASE-T has a slightly higher latency in comparison to most other 10GBASE standards. What’s more, 10GBASE-T offers the most flexibility, the lowest cost media. And because of its backward-compatibility with 1000BASE-T, 10GBASE-T can be deployed based on existing 1GbE switch infrastructures that are cabled with CAT6 and CAT6A (or above) cabling, keeping costs down while offering an easy migration path from 1GbE to 10GbE.


The deployment of 10GbE infrastructure should be much easier, with these media options in mind, coupled with your own such project considerations as cost, power consumption and distance reach. Fiberstore, as a professional fiber optic product supplier, offers a broad selection of fiber and copper cables, including SFP-10G-AOC1M mentioned above. For more information about 10GbE media options, you can visit Fiberstore.