How to Realize Single Fiber Connection in WDM System?

As we all know, fiber optical networking has two transmission ways: dual fiber transmission and single fiber transmission. The difference between them is that the former one requires two fibers—one is for transmitting and the other is for receiving, while the latter only uses one fiber for both transmitting and receiving. Single fiber transmission emergence reduces network deployment cost, especially in WDM systems. This blog intends to introduce how to achieve single fiber connections in CWDM and DWDM networks.

Understanding Single Fiber Transmission

Single fiber transmission, also called bidirectional (BiDi) transmission, sends data in both directions with one strand fiber. For enterprise networks or telecom networks providers who are with limited budgets and fiber capacity, the single fiber transmission is no doubt an ideal choice.

In addition, single fiber transmission is popular in many places.

  • Point to Point, Ring or linear Add and Drop, where installing new fiber is difficult or expensive
  • Enable segmentation of the enterprise traffic over 2 different fibers rather than using the same fiber for both segments
  • Increase reliability to an existing dual fiber solution by using one fiber for working and one for protecting
Single Fiber Solution in CWDM Systems

CWDM technology enables multiple channels (wavelengths) to be transmitted over the same fiber cabling and is able to provide a capacity boost in metro and access networks. Each channel carries data independently from each other, which allows network providers to transport different data rates and protocols (T1, T3, Ethernet, Serial, etc) for different customers or applications. Then how to achieve single fiber transmission in CWDM networks?

Here is an example of single fiber solution in CWDM system.


The above picture shows how different CWDM wavelengths are transmitted in a single fiber CWDM link. In this link, two 8CH CWDM Mux/Demuxs are required to transmit sixteen different wavelengths. At site A, there is a single fiber 8CH CWDM Mux/Demux using eight wavelengths for transmitting and the other different eight wavelengths for receiving. At site B, another 8CH single fiber CWDM Mux/Demux is deployed. But the wavelengths for TX and RX are reversed. And one single fiber connects the two CWDM Mux/Demux.

Notes: the use of transceivers connected with the CWDM Mux/Demux should be based on the wavelength of the TX side.

Single Fiber Solution in DWDM Systems

DWDM is an optical multiplexing technology to increase bandwidth over existing fiber optic networks, especially in long haul transmissions. And it can support more channels and higher traffic services such as 40G, 100G of LAN/WAN. Since the cost of DWDM components is high, the single fiber transmission is necessary.

DWDM single fiber transmission can be achieved with the use of single fiber DWDM Mux/Demux. As the following picture shows.

DWDM single fiber solution

The picture shows a single fiber 8CH DWDM Mux/Demux with expansion port used for single fiber transmission. Similar to the single fiber CWDM Mux/Demux above, this DWDM Mux/Demux also uses eight wavelengths for transmitting and another eight wavelengths for receiving. In general, the DWDM Mux/Demux should be used in pairs in single fiber bi-directional transmission, and the Mux/Demux port for specific channel must be reversed. Besides, more channels can be added into the links with the expansion port.

This 8CH DWDM Mux/Demux single fiber solution allows extremely high utilizing of a single fiber strand to pass up to 16 wavelengths, optimizing the use of fiber optic cables. And in long distance transmission, optical amplifier also can be utilized.

FS.COM Single Fiber Solution

FS.COM supplies various single fiber CWDM & DWDM Mux/Demux and optical transceivers. Here is part of our Mux/Demux products.

Single Fiber CWDM & DWDM Mux/Demux Product ID Operating Channel
cwdm mux-demux 43779 Tx/Rx:1310/1290, 1350/1330, 1390/1370, 1430/1410, 1490/1470, 1530/1510, 1570/1550, 1610/1590
DWDM mux-demux 50117 Tx/Rx:C21/C22,C23/C24,C25/C26,C27/C28, C29/C30,C31/C32,C33/C34,C35/C36

Analysis of OEO Transponder Application in WDM Network

Anyone who has experiences of deploying WDM networks, either DWDM or CWDM networks, may be familiar with OEO transponder. Since in WDM network deployment, especially for long haul transmission, OEO transponder plays an important role. OEO transponder, also known as WDM transponder, means optical-to-electrical-to-optical. That is to say, it converts an optical signal to an electrical signal, and then recovers it to an optical signal. In some cases, OEO transponder serves as fiber mode converter or repeater for long distance transmission.

OEO transponders

Functions of OEO Transponder
Wavelength Conversion

As we all know, when add a CWDM Mux/Demux or DWDM Mux/Demux into a WDM network, there is a requirement to convert the optical wavelengths like 850nm, 1310nm and 1550nm to CWDM or DWDM wavelengths. Then the OEO transponder comes to assist. The OEO transponder receives, amplifies and re-transmits the signal on a different wavelength without changing the signal content.

Fiber Mode Conversion

It’s know to us that multimode fiber optic cables (MMF) are often used in short distance transmission, while single mode fiber optic cables (SMF) are applied in long optical transmission. Therefore, in some network deployment, considering the transmission distances, MMF to SMF or SMF to MMF conversions are needed.

Signal Repeating

In long haul fiber optic transmission, OEO transponder also can work as repeater to extend network distance by converting wavelengths (1310nm to 1550nm) and amplifying optical power. The OEO converter converts the weak optical signals from the fiber into electrical signals, and regenerates or amplifies, then recovers them into strong optical signals for continuous transmission.

Analysis of OEO Transponder Application Case

Having known about the function of OEO transponder, here let me take some application cases as examples to illustrate its applications clearly.

Case One

The distance between site A and site B is about 165km, and there is a repeater station C. The distance between A and C is 90km. The client needs to build connection between A and B. Just like the following picture shows.

OEO transponder

In this solution, three OEO transponders are used in this links according to the requirements of the client. The use of the first OEO converter at site A is to convert the signals from MMF to SMF, achieving the long distance transmission between site A and C. The second OEO transponder re-generates and amplifies the optical signal, then convert the it from dual fiber to single fiber. At site B, the OEO transponder re-amplifies the optical signal and recovers it to multimode transmission.

Advantages of this solution: use OEO transponder to achieve fiber mode conversion and long distance transmission; make full use of the OEO transponder (retime, regenerate and reshape) to realize high quality connections; save cost by using the OEO transponder.

Case Two

This solution is more complicated than the first one. There are three sites with fiber links between them. The distance between site A and B is 84km, and site B and C is 1km. Site A and C is 84km too. All the 10G connections are dual fiber transmission. Here is a simple picture of this solution.

OEO transponder application

As we can see in the figure, to build DWDM networks between these three sites, six OEO transponders are deployed. Each site uses two OEO transponders. The OEO transponder at site A converts the 10G-LR signals into 10G DWDM wavelengths, then the wavelengths are multiplexed by the DWDM Mux. At site B, the separated wavelengths are recovered to 10G-LR signals through the OEO transponder. The transmission between site B and C, site A and C are similar to the transmission between site A and B. In addition, there are two EDFAs in each two long distance transmissions.

Advantages of this solution: using OEO transponder for wavelength conversion. Converting common 10G signals into DWDM wavelengths and transmitting them with DWDM MUX/DEMUX increase the network capacity easily. At the same time, it also reduces the damage of optical transceivers.


OEO transponder is an important components in optical networks. This post gives a simple analysis of OEO transponder application case. Hope it’s useful for you. FS.COM supplies high quality 10G OEO converters like SFP+ to SPF+ and XFP to XFP, and 40G WDM transponder like QSFP+ to QSFP+. If you want to know more detailed information, please contact us via

How to Calculate DWDM System Loss in Long Haul Transmission

Nowadays, high capacity network is needed to deal with large amount of data transfer. The application of DWDM (dense wavelength division multiplexing) system is a commonly used technique to enhance network capacity. Due to its complexity caused by various components like EDFA and dispersion compensating module (DCM), it may be difficult to calculate the loss over the whole links, especially in long haul transmissions. Then, how to calculate the budget loss of a DWDM system in long haul transmission? This post will illustrate the method to solve this problem.

Causes of Loss in Long Haul DWDM System

Loss budget is always one of the crucial problems that need to be considered before deploying a network. Any components in optical links will introduce loss. For example, when add a DWDM mux to a DWDM network, it will cause insertion loss which is the total optical power loss (often measured by dB) caused by the insertion of an optical component. In long haul DWDM system, there are several causes of link loss.


DWDM Muxs are the components that combine several different wavelengths so that they can be transferred on one fiber. And Mux is a passive device that cannot strengthen the light signals. Therefore, there is a big insertion loss of DWDM Mux. The lower the insertion loss is, the less network deployment cost is needed. Although Mux vendors are always endeavoring to reduce the insertion loss, there are still big differences between DWDM Muxs of many vendors. Here is a histogram to provide a direct-viewing comparison. From the graph, we can see the maximum insertion loss of FS.COM 40CH DWDM Mux is only 4.5dB.

40ch dwdm mux insertion loss comparison

DCM (Dispersion Compensation Module)

Dispersion compensation module is to fix the optical signals that have been deformed by chromatic dispersion. Therefore it is important to use at the receiver end to recover the signals by reshaping the optical pulse. This component also brings a good amount of insertion loss.

OADM (Optical Add/Drop Multiplexer)

OADM is another device that introduces insertion loss for DWDM networks. Since it allows individual or multiple wavelength channels to be added or dropped from an incoming link, as the signal pass from the common port to add/drop port or from the add/drop port to the common port, insertion loss occurs.

Except for the components that cause loss for the whole links, fiber optic cables also introduce loss which increases as the distance gets longer. Besides, in order to achieve balance signal power for receivers, designers often use EDFA to boost or add gain to optical signals on a fiber optic cable.

How to Calculate the Loss Budget of DWDM System?

In order to illustrate the calculation process clearly, here takes a case from FS.COM as an example. This deployment solution is designed for a client in UK. The following picture just shows part of the solution design.

40ch dwdm mux solution

The distance of site A and site B is 132.4km. From the figure, we can see optical components used includes 40CH DWDM Mux/Demux, booster EDFA, Pre-amplifier, 2CH OADM, etc. And there are also optical attenuators which are not show in the figure. Here is a chart indicating the loss or gain value of them which can be found in FS.COM website.

Components Insertion loss/Gain
Booster EDFA 23dB
Pre-amp EDFA 26dB
Attenuator 0-30dB

Now let’s start to calculate the budget loss in this link. Considering the whole solution is so complicated that this calculation is just to give an example of calculating the budget loss between site A and site B. And the calculation starts from site A to site B unidirectional, as the arrow line shows.

  • The loss between the 40CH DWDM Mux and the router is -8.5dB, caused by the use of an optical attenuator.
  • Then the signals pass through the DWDM Mux, the output power is:-8.5dB-4.5dB =-13dB.
  • Since the booster EDFA gain is +23dB, the signal output power of this EDFA is: -13dB+23dB= +10dB.
  • Calculation of the fiber optic cable, the total loss is: -0.22dB/km x132.4km = -29.13dB. The input power of the pre-amp EDFA is: +10dB-29.13dB = -19.13dB.
  • The pre-amp EDFA gain is +26dB, then the output power of this EDFA is +6.87dB.
  • There is an attenuator placed after the pre-amp EDFA, the output power after the attenuator is: +6.87dB-18dB = -11.13dB.
  • The output power of the booster EDFA is: +23dB-11.13dB=+10.67dB. That’s the output power of site B.

For DWDM network system, how to control the power loss is important, which requires network designers calculate the budget loss before deploying the systems. This post gives an example from our client to calculate the loss in a DWDM network. FS.COM offers both necessary optical components and solutions for your networks. If you are interested, please contact us via

Options Upgrading to 100G Connection

With growing data traffic volume in recent years, the existing 10Gb/s optical networks are becoming saturated, which drive the great need for 40G and 100G networks. In turn, 100G network also can bring benefits for network operators. For example, 100G network can reduce the cost per bit, improve the utilization of existing fiber and reduce the network delay. This post intends to explore the options to get 100G connection.

100G Connectivity Challenges

As we all know, existing 10G network use two fibers in either a SC duplex or a LC duplex connector to realize data transmission. But different from this transmit type, data in 100G network often get multiplexed and transferred over the 4 or 10 parallel wavelengths on a single fiber, which means the lanes of the two kinds of networks are a little different. This is one problem that should be considered when deploy 100G connections.

Except for that, the cost is another problem needed to be resolved. No matter the 40G or 100G, both of them require more fibers and optical connectors, resulting in increasing cost. For example, 40G Ethernet and 100G Ethernet over multimode fiber uses parallel optics at 10 Gb/s per lane. One lane uses one fiber for each direction of transmission. So 40G Ethernet requires eight fibers. And 100G Ethernet requires 20 fibers.

Options Upgrading to 100G Connections
Option One: Upgrading to 100G Connections with DWDM Mux

With the boom application of cloud services, telemedicine, video on demand, etc, data rate migration encompassing the entire optical network. Therefore, some core networks have deployed DWDM to release this bandwidth explosion. With large capacity transmission ability, DWDM technology offers a cost-effective method to meet the bandwidth requirements.

Complementing the existing 10Gbps DWDM system with 100Gbps upgrades

In many cases, to avoid the high cost and save cost, some operators often use one DWDM Mux to add one or more 100G services into the same fiber. The picture is showing one of that cases. In this case, 10G and 100G services are multiplexed by two separated 100GHz DWDM MUX. Owing to the 100G services are easy to be affected by dispersion, so the optical amplifier and DCM (Dispersion Compensation Module) are added in the links to boost the signal power. Then the 10G and 100G services are bundled together by using the interleaver which is an optical router often used in DWDM system. And finally the 100G connection is achieved.

Option Two: Upgrading to 100G Connections with MTP Assemblies

Nowadays there are various products on the market to support 100G connections. The most often used is 100G CFP, 100G QSFP28 and MTP optical cables. For many network operators, the option one that uses 100GHz DWDM Mux, optical amplifier, DCM and 100G optical transceivers maybe a little expensive. However, except for using DWDM Mux to achieve 100G connections, there is another choice. It is to achieve 100G connections with MTP assemblies.

100G Connection Deployment

In this connection, the 100G connection can be realized by using a MTP cord with a 24-fiber MTP connector on one end and two 12-fiber MTP connectors on the other end.

Notes: this simple chart just illustrates a short distance 100G connection.

Besides, since 10G connections usually use common fiber optic cables with LC or SC connectors, and the 40G connections use 12-fiber MTP cables, while 100G connections utilize 24-fiber MTP connections. Therefore, migrating from 10G/40G to 100G can be realized. Look at the basic 10G and 40G deployment scenario.

10G 40G network deployment

From the picture we can see, the similarities of these connections are that they are using MTP cables. Just change the cable types and then migrating from 10G to 40G and 100G are possible.


100G connection is the trend in the future data centers. This post introduces two options to achieve 100G connections with existing optical components. According to different requirements, you can choose a suitable solution. FS.COM supplies various optical components to meet diverse applications in data centers and enterprise networks. If you want to know more details about 100G networks, please visit our website

Solutions to Achieve Long-haul Transmission With DWDM Systems

In order to increase the transmission distance of optical signals, many technologies, like the TDM (time division multiplexing) and WDM (wavelength division multiplexing), have been used. Except for that, several optical components like single mode fiber optic cables, optical amplifiers and dispersion compensating modules (DCMs) are also put into use to realize the goal. Today, this article intends to illustrate the solutions to achieve longer transmission distances with DWDM technology.

Solutions to Extend Transmission Distances

When it comes to long-haul optical transmissions, DWDM (dense wavelength division multiplexing) is a topic that cannot be ignored. DWDM technology enables different wavelengths to transmit over a single optical fiber. Different wavelengths are combined in a device—Mux/Demux which is short of multiplexer/demultiplexer. The DWDM Mux/Demux provides low insertion loss and low polarization-dependent loss for optical links. Here take a 8CH DWDM Mux/Demux for example to illustrate how to extend distance in long haul transmission.

Solution One

The first solution is suitable for applications that are less than 50km. The picture below shows a unidirectional application with 8CH DWDM Mux/Demux. As we can see, in this links, the DWDM Mux/Demux transmits 1550nm signal over one single mode fiber. The eight different signals from the transmitters are multiplexed into 1550nm signal by the 8CH DWDM Mux. Then they go through the single mode fiber and are separated into the original wavelengths by the DWDM Demux. The use of DWDM Mux/Demux and single mode fiber allows the system to transmit over 50km without optical amplifier or DCM.

8 channel mux demux in long haul transmission

Notes: this solution is the basic application of DWDM Mux/Demux in a relative long distance comparing to CWDM technology which suits short distance deployment.

Solution Two

Different from the first solution, if the link distance is longer than 50km, this solution can be taken into account. Optical signal loss will become greater as the links are getting longer, which means an optical amplifier module or dispersion compensator is needed. Therefore, to achieve a satisfying signal quality in long-distance transmission, an EDFA which can boost the weakened optical signals is added in this solution (as shown in the picture below).

edfa in long haul transimission

Solution Three

This DWDM configuration is similar to the former one, but with the EDFA, the link distance on the single mode fiber is up to 200km. However, sometimes an EDFA is not enough to achieve a quality signal, especially in some long haul systems like CATV system. Because these systems often have a high requirement for the quality of optical signal. Therefore, as we can see in the following picture, except for the DWDM Mux/Demux and EDFA, there is also a DCM.

edfa and dcm in long haul transmission

This solution is a point-to-multipoint long haul system deploying a DCM to extend the transmission distance. From the picture, the EDFA is placed midway between the transmitter and receiver in the transmission path. And in order to ensure the quality of the whole transmission, a DCM module is added in this link to deal with the accumulated chromatic dispersion without dropping and regenerating the wavelengths on the link.

Notes: all the three solutions are unidirectional transmission on single mode fiber cables. If a network requires bidirectional transmission to transfer eight signals, you can use a 16CH DWDM Mux/Demux over single fiber or a 8CH DWDM Mux/Demux over dual fiber.


WDM technology, especially the DWDM, is the critical step to go into the super-long distance transmission in optical communication. This post mainly introduces three basic solutions to realize long haul transmission with DWDM Mux/Demux. All the components including the DWDM Mux/Demux (both 8 channels and 16 channels), EDFA, DCM and optical modules are available in FS.COM. If you have any needs, please contact us via

Advantages and Disadvantages of Direct Attach Twinax Cable

Driven by need for high speed Ethernet and increasing services like Cloud and virtual data center, many data centers have been loaded with numerous cables and various equipment. Due to this case, shortage of data center space is common but it’s getting difficult and expensive to build new or expand existing locations. Today this post intends to introduce a type of cable—direct attach twinax cable, which can solve this problem effectively.

Overview of DAC

Direct attach twinax cable is a type of copper cable similar to coaxial cable, but it has SFP+, QSFP+ or QSFP28 plus at each end integrated. DACs are usually used in data centers for short transmission between racks. Generally, according to the construction differences, the DAC comes in two types: passive DAC and active DAC. Passive DAC are suitable for short distances up to 10 m and active DAC has a little longer transmission distance up to 15m at 10Gbps or 40Gbps, because it has an active component to boost/receive signal. And passive DACs require no power for internal electronics, which avoid consuming power or produce heat. While active DAC comes in reverse, it needs power to make its internal circuits work properly.

On today’s markets, in order to satisfy the ever growing need for cost-effective delivery of more bandwidth, there are mainly three kinds of DAC according to the transmission rate: 10G SFP+ DAC, 40G QSFP+ DAC and 100G QSFP28 DAC.

10G SFP+ DAC offers the high density, low cost and low power solutions for today’s 10G Gigabit Ethernet connections. With its SFP+ interface, this twinax cable allows interconnects with hot-pluggable optical transceivers and Ethernet switches in data centers. As shown in the picture below, two Cisco catalyst switches are connected with a 10G SFP+ DAC.

two Cisco Catalyst 4948E-F Switches directly with 10G sfp+ dac

40G QSFP+ DAC offers a way for 40G Gigabit short distance connections between QSFP ports switches. As its name shows, 40G QSFP+ DAC has QSFP+ connectors on both ends. And it uses integrated duplex serial data links for bidirectional communication. 40G QSFP+ DAC is a little different from 10G SFP+ DAC. Because it has another two breakout forms: 40G QSFP+ to 4XSFP+ DAC and 40G QSFP+ to 4xXFP DAC. These breakout DACs can be used to migrate from 10G to 40G.

two Cisco switches connected by 40 QSFP+ to QSFP+ DAC cable

The last one is 100G QSFP28 DAC. The 100G QSFP28 DACs are high speed cable to meet and exceed 100G Gigabit Ethernet, providing connectivity between devices using QSFP28 ports. The 100G QSFP28 DAC includes QSFP28 to QSFP28 and QSFP28 to 4xSFP28 breakout DAC. These interconnect cables provide four channels of high speed differential signals with data rates ranging from 25Gbps up to potentially 40Gbps.

Advantages and Disadvantages of DAC 

DACs come into play in data centers mainly because of two factors which also show its superiority. We all know that denser equipment in the data center or server rooms will consume more electrical power and produce more heat. That means more cooling systems are required. However, DACs have the potential to reduce the overall power consumption and heat dissipation, which help network operators save cost. Another factor is that DACs are robust and do not need patch panels or additional cables when connected to devices, as is the case with an optical module. The modules on both ends make them sturdy and reliable as well as space-saving.


Nothing can be perfect, so do the DACs. Although they can save space and cost for data center managers, the drawbacks still exist. As the mainly element of DACs is copper, it is heavy and bulky, causing difficulties for management. What’s more, if DACs are deployed in high volume, the cable diameter and cable stiffness are another problem that should be considered. In this case, active optical cables (AOCs) seem to be a better choice, for they are made of thinner and more pliable optical cable.


DACs provide a low power consumption and high-speed solution for data center interconnections. With the ability to support data rate of 10G, 40G and 100G, they are now widely used in optical links. All the DACs mentioned above are supplied in FS.COM. If you need to know more details, please visit or directly contact us via

How to Optimize Your Network Performance with LC Assemblies?

High-density and compact data center cabling has become the consequent trend as the rapid development of fiber optic communication. Under this trend, LC assemblies, like the LC connector, LC adapter and LC attenuator, are more and more popular in the applications of cable television (CATV), fiber-to-the-home (FTTH) and dense wave division multiplexing (DWDM) Markets. Today this post intends to explore how to optimize network performance with LC assemblies.

LC Adapter for Easy Installation

It’s familiar to us that fiber optic adapters are used to connect fiber optic components with the same or different interfaces. Due to their ability to interconnect two connectors, they are widely applied in optical management systems. And nowadays there are various LC adapters available in the market for both single mode and multimode applications. Take the quad LC adapter for example, Quad LC adapters, designed for high-density applications, provide 4-position LC adapter solution in a traditional duplex SC footprint. The mating sleeve can connect four duplex or eight simplex LC fiber optic cables, saving more space and bring more flexibility.

Quad Plastic LC Fiber Optic Adapters

LC Attenuator for Better Transmission Quality

As we all know, signal strength needs to be reduced in some case. For instance, if a transmitter delivers too much light power, at the receiver end the power must be reduced by using fiber optic attenuator. Or it may degrade the bit error ratio (BER). LC attenuator is a type of widely applied fiber optic attenuator. It is designed to provide horizontal spectral attenuation over the full spectrum vary from 1260nm to 1620nm in single mode transmission. Therefore the LC attenuators can expand the capacity of optical networks by using the E-band (1400-nm window) for optical transmission.

LC fiber optic attenuator

LC HD Plus+ Fiber Cable for High Density Application

Designed with flexible “push-pull tab” uniboot connector, bend insensitive fiber and ultra-low insertion loss, LC HD plus+ fiber cables are the best choice for high-speed, high-bandwidth 1GbE and 10GbE networks in data centers. People with working experiences in data centers may know it’s not an easy task to add or remove one connector in numerous network cables. But with the push-pull tab uniboot connector, this problem can be solved perfectly. Firstly, the LC uniboot connector encloses two fibers firmly in a single cable, saving cable management space greatly. Secondly, the push-pull design enables connectors to be extracted or inserted into the port freely, which simplify the connectivity problems of limited access to the connector.

LC HD Plus+ Fiber Cable

LC Mux/Demux for More Flexibility in WDM Network

CWDM and DWDM Mux/Demux play an important role in combining data rate of different wavelengths over the same fiber cable to increase network capacity. No matter CWDM or DWDM Mux/Demux, there are several types of ports on them to ensure the normal function: channel port and line port. Of course, some Mux/Demux also have an expansion port and monitor port. A LC Mux/Demux means the LC Mux/Demux has LC connector for interfacing. It’s known to us that LC design is popular in fiber optic links. Mux/Demux with LC interface is easy to install and add WDM capacity to an existing network.

The following picture shows how to use two CWDM Mux/Demux at the same time to increase the wavelengths and expand the network capacity. The 8 CH and 4CH CWDM Mux/Demux are connected using the expansion port (LC interface).



LC interface is the result of increased demands for smaller easier-to-use fiber connectivity. And a wide range of optical components with LC interface are widely used in optical networks. This article just introduces parts of them. Some other LC assembles such as optical transceivers, LC pigtails and LC adapter panels are available in Fiberstore. If you want to know more details, please visit FS.COM.

100G QSFP28 Transceiver Overview and How to Choose It

It’s no denying that today’s data centers are moving from 10G to 40G and 100G quickly. On this road, data explosion is getting faster, which result in great demand for cost-effective 100G optics. And the commonly used 100G transceivers are CFP, CFP2, CFP4 and QSFP28, especially the QSFP28. Today this article mainly introduces four types of 100G QSFP28 transceiver and the comparison between them to help you choose a suitable one.

Overview of 100G QSFP28 Transceiver
100G QSFP28 SR4 Transceiver

The 100G QSFP28 SR4 transceiver is a full-duplex optical module, offering four independent transmit and receive channels, each capable of 25Gb/s operation for an aggregate data rate of 100Gbps to 100 meters on OM4 multimode fiber (MMF). It’s fully compliant with QSFP28 Multi-Source Agreement (MSA) and can offer increased port density and total system cost savings for future data center and networking use. When connected to transmission links, an optical fiber ribbon cable is plugged into the QSFP28 modules receptacle via the MTP/MPO connector, and the guide pins inside the receptacle ensure the proper alignment. Besides, this QSFP28 transceiver offers high functionality and feature integration, accessible via a two-wire serial interface which is available for more complicated control signals and digital diagnostic information.


100G QSFP28 LR4 Transceiver

The 100G QSFP28 LR4 transceiver is a fully integrated 4x25Gbit/s optical transceiver module, designed for use in data centers and high performance computing network links on up to 10km of single mode fiber (SMF). They are compliant with QSFP28 MSA, IEEE 802.3ba and IEEE 802.3bm CAUI-4. When connected to data transmission links, it converts four input channels of 25Gb/s electrical data to four channels of LAN WDM optical signals and then multiplexes them into a signal channel for 100Gb/s optical transmission. While on the receiver side, the module demultiplexes the 100G optical signals into four output channels and converts them into electrical data.


100G QSFP28 PSM4 Transceiver

Defined by the 100G PSM4 MSA, PSM4 is a little different from QSFP28 SR4 transceiver. It uses four parallel lanes (four transmit and four receive) operating on each direction. Each lane carries 25G optical transmission. Therefore, eight single mode fibers are needed when PSM4 is deployed in transmission links. And the reach of PSM4 is up to 500m on single mode fiber, compensating for the transmission distance defect between QSFP28 SR4 and QSFP28 LR transceiver.


100G QSFP28 CWDM4 Transceiver

CWDM4 routes four 25G optical transmissions down a single fiber, which is like the PSM4. But it has longer reaches of up to 2km on SMF. And CWDM4 uses multiplexer and de-multiplexer to reduce the number of fibers to two rather than eight. When connected into transmission links, on the transmitting side, signals are multiplexed into one channel and transmitted through the SMF; then on the receiving side, the incoming signals are demultiplexed into four separated channels (shown as below).


How to Choose?

With a number of 100G optical transceivers emerged, many factors should be taken into consideration when choose suitable transceivers. The key features of the 100G QSFP28 transceivers are listed below.

100g QSFP28 Transceivers

As shown in the table, cable type, interface type, fiber count and reach are needed to be considered when purchasing transceivers. For example, in the terms of reach, except the shortest (QSFP28 SR4) and the longest (QSFP28 LR4), PSM4 and CWDM4 are battling out in the 2km range. Here is a simple chart that may help to illustrate the difference between the two. As have mentioned above, PSM4 doesn’t use MUX/DEMUX, which determines its price is lower than CWDM4. However, as the transmission distance increases, the cost will grow quickly since it deploys eight-fiber transmission links.


In summary, there are various types of 100G transceivers on the market. Different companies and operators have different requirements for their links and applications. So choosing a suitable 100G QSFP28 transceiver should be based on your practical situations. If you want to know more about 100G QSFP28 optical transceivers, welcome to visit FS.COM.

How to Choose a Suitable Wireless Access Point for Business?

Wi-Fi technology has improved greatly in recent years. It has great impact on our life style and work habits. As an important component in this technology, wireless access points (APs) has become more prevalent than before, for they can provide a convenient way to wired networks. But it’s not one-size-fits-all, especially when it comes to businesses. They may suits large office spaces with heavy traffic, but not small offices with limited users. Of course, all situations cannot be treated as the same. Let’s take a look at how to choose a suitable wireless access point for your business.

What Can a Wireless Access Point Do for Your Business?

A wireless access point is a hardware device or configured node in a local area network (LAN) that connects to a wired router, switch, or hub via an Ethernet cable, and projects a Wi-Fi signal to a designated area. It can be used both in an office or a large building.

wireless asscess points applications

As we all know, business network is not like a home Wi-Fi network. The latter one only has a limited number of devices at one time, but the former need to handle numbers of connections simultaneously. Generally, wireless access points can handle over sixty connections each at the same time. When employees or guests connecting with desktops, laptops, tablets or mobile phones, they can get access to your wired network easily and quickly.

In a word, here are what the wireless access points can bring for your business:

  • Improve productivity by allowing employees to access company resources from anywhere in the workspace
  • Wireless access points compatible with PoE eliminate the need to run separate power line or install an outlet near the access point, which saves cost and installs time
  • Wireless access points supporting Captive Portal and Access Control List (ACL) give you more convenience to manage your Wi-Fi networks
Tips on Choosing Suitable Wireless Access Points

It’s not easy to select a suitable wireless access point for business networks if considering several factors. Well, it’s no doubt that the standards should be put in the first place. Therefore, I’ll talk more about other practical factors that may be ignored.

wifi access points


As technologies are evolving so fast, it’s important to choose wireless access points that firmware upgrades. It is also beneficial if the upgrades can be done from a central access point, which automatically allocates the upgrade to other access points on the network.

Coverage Options

A wide range of wireless access points available for your business to choose from in the market. Depending on the area you’ll need to cover will be a main determining factor here. Will they be for indoor or outdoor use? Is there a need for considerable shielding for outdoor use? Before you adding the APs in your cart, these questions need to be answered at first.

Working Temperature

Wireless access points have a good working performance in a normal environment like office or mall. But we cannot exclude some extreme temperatures occur, especially in outdoor use. So have a clear view of the working temperatures with wireless access points is the key to determine how long your APs can work for you.


Once you have known clearly which kind of wireless access points is suitable for your business networks, it’s time to compare the price. It’s obvious that price plays a vital role in the selection of wireless access points. According to your actual conditions to choose a suitable wireless access point. Be aware of the features that can simplify the process of installation.

Except for the considerations above, other factors such as speed and mounting style also need to be taken into account.


By installing access points through the workplaces, employees can roam freely from room to room without experiencing network interruptions. Their devices shift seamlessly from one access point to the next without dropping the connection through the workplaces, improving work efficiency greatly. Therefore, choosing the best wireless access points is important.

Bridge Copper to Fiber With PoE Media Converter

It’s common to see in modern society that many enterprise networks must support a wide range of installation environments located indoors and out. Considering this, a wide range of media converters and power supply options are important. And with the great benefits of fiber optic cables being accepted widely, PoE media converter seems to be a better choice for enterprise networks. Today this article intends to explain what PoE media converter can bring for managers and its applications.

PoE Media Converter Basis

PoE media converter is a type of fiber-to-copper media converter. It enables enterprises to power their network devices over the existing copper connections. With its PoE injector, PoE media converters can power devices like IP phones, video conferencing equipment, IP cameras and Wi-Fi devices over copper UTP cabling. Besides, they are available in a variety of multi-port configurations, including dual RJ-45 and dual fiber ports, and they can support fixed fiber connectors or SFP (Small Form Pluggable) transceivers.

PoE Media Converter

Once PoE media converters are connected into network systems, they are usually close to the PDs (Power devices) like IP cameras and wireless access points. And when they work, fiber is run to the power source via the SFP socket, and PoE is distributed over UTP cabling to the power devices via RJ45 port.

Network Design Options Provided by PoE Media Converter

PoE media converters bring great benefits for network deployments. For example, they eliminate the need for power supply devices, power cables and outlets that would be required for remote device. In addition, they also provide flexible network design options. Here are some examples.

PoE Media Converter with Single Fiber Ports

As shown in the following picture, single fiber ports are deployed in star topologies with a point-to-point style layout with the fiber switch in the center of the network.

PoE Media Converter with Single Fiber Ports

PoE Media Converter with Dual Fiber Ports

Option 1: daisy chain design. This design uses dual fiber ports to support connections in a liner daisy chain configuration. It suits long-haul applications along subways and rail lines.

PoE Media Converter with Dual Fiber Ports 1

Option 2: fiber ring design. In this fiber ring architecture, traffic can flow in both directions. In the picture below, a switch connects three PoE media converters to form a ring. If a fiber failure occurs in it, the switch can reroute the traffic in the opposite direction.

PoE Media Converter with Dual Fiber Ports 2

Option 3: redundant fiber design. This network structure uses two fiber connections. One is active and carries the data traffic. The other is a protection fiber port that back-up a fiber failure switch-over of less than 50 milliseconds.

PoE Media Converter with Dual Fiber Ports 3

Applications of PoE Media Converter

As we all know, in order to break out the distance and bandwidth limitations of copper cables, fiber optic cable is a good alternative. PoE media converters can convert copper to fiber and provide power at the same time, making it popular among enterprise networks. There are three main applications of PoE media converters.

  • Fiber to IP cameras. The PoE media converters have fiber uplink ports and downlink ports. And in most applications, two IP cameras at each location can be connected through the dual RJ-45 ports of a PoE media converter.
  • Fiber to wireless access points. PoE media converters enable wireless access points to be installed in office buildings, airport, hotels, public areas or other places needed.
  • Fiber to the desktop. The PoE media converters provide fiber to copper media conversion, and they send data and power to desktop items such as IP phones and video conferencing equipment.

PoE media converters provide a cost-effective way to extend distances over fiber optic cabling to PoE powered devices (PDs). In this article, four network designs with PoE media converters and three applications of them are illustrated simply. If you want to know more details about PoE media converters, please visit FS.COM.

Related article: Things You Need to Know About Power Over Ethernet (PoE)

Related article: How Much Do You Know About PoE?