Author Archives: Katherine.Wang

EDFA vs Raman Optical Amplifier

Although the fiber loss limits the transmission distance, the need for longer fiber optical transmission link seems never ending. In the pursuit of progress, several kinds of optical amplifiers are published to enhance the signals. Hence, longer fiber optical transmission link with big capacity and fast transmission rate can be achieved. As the EDFA and Raman amplifiers are the two main options for optical signal amplification. which one should be used when designing long fiber optical network? What are the differences of the two optical amplifiers? Which one would perform better to achieve the long fiber optical link? And which one is more cost effective? Let’s talk about this topics.

What’s EDFA Amplifier?

EDFA (Erbium-doped Fiber Amplifier), firstly invented in 1987 for commercial use, is the most deployed optical amplifier in the DWDM system that uses the Erbium-doped fiber as optical amplification medium to directly enhance the signals. It enables instantaneous amplification for signals with multiple wavelengths, basically within two bands. One is the Conventional, or C-band, approximately from 1525 nm to 1565 nm, and the other is the Long, or L-band, approximately from 1570 nm to 1610 nm. Meanwhile, it has two commonly used pumping bands, 980 nm and 1480 nm. The 980nm band has a higher absorption cross-section usually used in low-noise application, while 1480nm band has a lower but broader absorption cross-section that is generally used for higher power amplifiers.

The following figure detailedly illustrates how the EDFA amplifier enhance the signals. When the EDFA amplifier works, it offers a pump laser with 980 nm or 1480 nm. Once the pump laser and the input signals pass through the coupler, they will be multiplexed over the Erbium-doped fiber. Through the interaction with the doping ions, the signal amplification can be finally achieved. This all-optical amplifier not only greatly lowers the cost but highly improves the efficiency for optical signal amplification. In short, the EDFA amplifier is a milestone in the history of fiber optics that can directly amplify signals with multiple wavelengths over one fiber, instead of optical-electrical-optical signal amplification.

EDFA Amplifier Principle

What’s Raman Amplifier?

As the limitations of EDFA amplifier working band and bandwidth became more and more obvious, Raman amplifier was put forward as an advanced optical amplifier that enhances the signals by stimulated Raman scattering. To meet the future-proof network needs, it can provide gain at any wavelength. At present, two kinds of Raman amplifiers are available on the market. One is lumped Raman amplifier that always uses the DCF (dispersion compensation fiber) or high nonlinear fiber as gain medium. Its gain fiber is relatively short, generally within 10 km. The other one is distributed Raman amplifier. Its gain medium is common fiber, which is much longer, generally dozens of kilometers.

When the Raman amplifier is working, the pump laser may be coupled into the transmission fiber in the same direction as the signal (co-directional pumping), in the opposite direction (contra-directional pumping) or in both directions. Then the signals and pump laser will be nonlinearly interacted within the optical fiber for signal amplification. In general, the contra-directional pumping is more common as the transfer of noise from the pump to the signal is reduced, as shown in the following figure.

Raman Amplifier Principle

EDFA vs Raman Optical Amplifier: Which One Wins?

After knowing the basic information of EDFA and Raman optical amplifiers, you must consider that the Raman amplifier performs better for two main reasons. Firstly, it has a wide band, while the band of EDFA is only from 1525 nm to 1565 nm and 1570 nm to 1610 nm. Secondly, it enables distributed amplification within the transmission fiber. As the transmission fiber is used as gain medium in the Raman amplifier, it can increase the length of spans between the amplifiers and regeneration sites. Except for the two advantages mentioned above, Raman amplifier can be also used to extend EDFA.

However, if the Raman amplifier is a better option, why there are still so many users choosing the EDFA amplifiers? Compared with Raman amplifier, EDFA amplifier also features many advantages, such as, low cost, high pump power utilization, high energy conversion efficiency, good gain stability and high gain with little cross-talk. Here offers a table that shows the differences between EDFA and Raman optical amplifiers for your reference.

Property EDFA Amplifier Raman Amplifier
Wavelength (nm) 1525-1565, 1570-1610 All Wavelengths
Gain (dB) > 40 > 25
Noise Figure (dB) 5 5
Pump Power (dBm) 25 > 30
Cost Factor Relatively Low Relatively High

Considering that both EDFA and Raman optical amplifiers have their own advantages, which one should be used for enhancing signals, EDFA amplifier, Raman amplifier or both? It strictly depends on the requirement of your fiber optical link. You should just take the characteristics of your fiber optical link like length, fiber type, attenuation, and channel count into account for network design. When the EDFA amplifier meets the need, you don’t need the Raman amplifier as the Raman amplifier will cost you more.

How to Enhance the Optical Signals for a Long DWDM System?

As we know, the longer the optical transmission distance is, the weaker the optical signals will be. For a long DWDM system, this phenomenon easily causes transmission error or even failure. Under this case, what can we do for a smooth, long DWDM system? The answer is optical signal enhancement. Only by enhancing the optical signals, can the DWDM transmission distance be extended. In this post, we are going to learn two effective solutions, optical amplifier (OA) and dispersion compensation module (DCM) to enhance the signals, for making a smooth, long DWDM system.

Optical Amplifier Solution

We used to utilize repeater to enhance the signals in fiber optics, which should firstly convert the optical signals into an electrical one, amplify the electrical signals, and then convert the electrical signals into an optical one again. Finally, you can get the enhanced optical signals. However, this method of enhancing signals can not only cause more signal loss, but also add unwanted noises in the actual signal. Taking these issues into account, the optical amplifier is more recommendable.

An optical amplifier is a device that enables direct optical signal enhancement or amplification. Its working principle is not so complicated as that of the repeater, while its performance is much higher. From the following figure, we can learn that the original reach of the DWDM system is limited to 80 km due to the signal loss. But with the optical amplifier, the signals are enhanced and the reach can be extended to 160 km. It is really an ideal option to enhance the signals for a long DWDM system.

Optical Amplifier (OA)

At present, there are mainly three major kinds of optical amplifiers, Semiconductor Optical Amplifier (SOA), Doper Fiber Amplifier (DFA), and Raman Amplifier (RA).

Semiconductor Optical Amplifier: as its name implies, the semiconductor in a SOA is used to offer the gain medium. This kind of optical amplifier has a similar structure to the FP laser diode. However, it is designed with anti-reflection elements at the end face that can greatly reduce the end face reflection. Meanwhile, the SOA features small package and low cost that suits for most users to enhance the optical signals.

Doper Fiber Amplifier: in a DFA, the doped optical fiber acts as the gain medium for signal amplification. When the DFA works, the signal to be amplified and a pump laser are multiplexed into the doped fiber. And then the signal is amplified through interaction with the doping ions. The most common DFA is the Erbium Doped Fiber Amplifier (EDFA). Its gain medium is a optical fiber doped with trivalent erbium ions that always enhances the signals near 1550nm wavelength. Undoubtedly, the EDFA is a great choice to enhance the optical signals.

Raman Amplifier: different from the SOA and DFA, the signal in a RA is amplified through the nonlinear interaction between the signal and a pump laser within an optical fiber. In details, two kinds, distributed and lumped Raman amplifier (DRA and LRA) are available on the market. The distributed one multiplexes the pump wavelength with signal wavelength through the transmission fiber to enhance the signals, while the amplification of the lumped one is provided by a dedicated, shorter length of fiber.

(Note: if you want to know more information about these three kinds of optical amplifier, you can take the previous post Optical Amplifier Overview as reference.)

Dispersion Compensation Solution

Apart from signal amplification, we can also use dispersion compensation to enhance the optical signals. Once the dispersion occurs, the signal will be tended to skew due to the different frequencies, which has a negative effect on the quality of signal transmission. At that moment, we use the dispersion compensation module to enhance the skew signal, for achieving a longer transmission distance. As shown in the figure below, the DWDM system is extended to longer than 80 km with the use of 80km passive dispersion compensation module.

Dispersion Compensating Module (DCM)

The dispersion compensation module is an important component for a long fiber optical link. It typically connects to the mid-stage of an OA like EDFA, in the long haul transmission system. Except for the 80km DCM mentioned above, FS.COM also provides other DCM modules that allow long transmission distance extension. The compensation distances can range from 10km to 140 km, as shown in the following table.

Module Type Description Price
FMT10-DCM 10KM Passive Dispersion Compensation Module, Plug-in Type, LC/UPC US$ 430.00
FMT20-DCM 20KM Passive Dispersion Compensation Module, Plug-in Type, LC/UPC US$ 650.00
FMT40-DCM 40KM Passive Dispersion Compensation Module, Plug-in Type, LC/UPC US$ 650.00
FMT60-DCM 60KM Passive Dispersion Compensation Module, Plug-in Type, LC/UPC US$ 1,100.00
FMT80-DCM 80KM Passive Dispersion Compensation Module, Plug-in Type, LC/UPC US$ 1,300.00
FMT100-DCM 100KM Passive Dispersion Compensation Module, Plug-in Type, LC/UPC US$ 1,400.00
FMT140-DCM 140KM Passive Dispersion Compensation Module, Plug-in Type, LC/UPC US$ 1,818.00


The optical amplifier has the ability to directly boost the weak signal, while the dispersion compensation module can reshape the deformed signal and offer a long compensation distance. Considering that the signal strength would become weak as the transmission distance increases, using the optical amplifier and dispersion compensation module to enhance the signals is very necessary when building a long DWDM system.

Economical Solutions for 10G to 40G Connection

With the accelerated development of optical network, there exist more and more capacity-hungry applications in 10G networks today. To solve this problem, experts put forward the 10G to 40G connection as an ideal solution. However, due to the high migration cost, we are prevented from making the migration. Do you also meet this issue? In this paper, it will offer several solutions for making 10G to 40G connections with less cost. Hope you can find one that suits your network.

10G to 40G Connection

Economical Solutions for 10G to 40G Short Connection

How to make a short link between 10G and 40G switches? You can choose the 40GBASE-SR4 QSFP+ module that supports the 40G network at length up to 150 m. Meanwhile, four 10GBASE-SR SFP+ modules are required. So is the MTP-LC harness cable for connecting QSFP+ and four SFP+ modules. In details, FS.COM offers OM3 MTP-LC harness cable supporting 40G connection up to 100 m and OM4 up to150 m. All these equipment mentioned above are available at FS.COM with good prices. For the details, you can learn from the following table.

Product ID Description Price
48558 Customized 40GBASE-SR4 QSFP+ 850nm 150m Transceiver US$ 49.00
48559 Customized 40GBASE-CSR4 QSFP+ 850nm 400m Transceiver US$ 59.00
50000 Customized 10GBASE-SR SFP+ 850nm 300m Transceiver US$ 16.00
31091 8 Fibers OM3 12 Strands MTP-LC Harness Cable US$ 26.00
48356 8 Fibers OM4 12 Strands MTP-LC Harness Cable US$ 28.00
66142 FS S3800-24T4S (24*10/100/1000Base-T+4*10GE) Switch US$ 400.00
29127 FS S5800-48F4S (48*1GE+4*10GE) Switch  US$ 1,700.00

If the link distance is longer than 150 m in your network, 40GBASE-CSR4 QSFP+ module may be a better choice. It can transmit the 40G signals longer, up to 400 m. As for the fiber patch cable, you can still chosse OM3 or OM4 MTP-LC harness cable. In general, the OM3 provided by FS.COM enables the connection up to 300 m, while OM4 up to 400 m. When making a short 10G to 40G migration, you can just choose FS.COM as an ideal fiber optical manufacturer. It offers all the equipment your network needs, including 10G and 40G switches, SFP+ and QSFP+ module and MTP-LC patch cable.

Economical Solutions for 10G to 40G Long Connection

Do you need to make a long 10G to 40G migration? FS.COM also offers several cost effective solutions. For example, up to 1km, 10km, 40km or even 80km 10G to 40G connection solutions. Let’s talk about the detail information of these solutions.

Spending Less for up to 40km 10G to 40G Connection

You can use the 40GBASE-PLRL4 QSFP+ and 10GBASE-LR SFP+ modules to support the 10G to 40G migration up to 1 km. The 40GBASE-LRL4 QSFP+ is also a good choice. As for the fiber patch cable, you can choose the 8 fibers single mode MTP-LC harness cable. Once the distance is longer than 1 km, your are suggested to use the 40GBASE-LR4 QSFP+ and 40GBASE-PLR4 QSFP+ modules. These two kinds of fiber transceiver modules enable the connection at lengths up to 10 km. It the link distance is up to 40 km, then you can use the 40GBASE-ER4 QSFP+ module. Here are the related equipment offered by FS.COM.

Product ID Description Price
48561 Customized 40GBASE-PLRL4 QSFP+ 1310nm 1.4km Transceiver US$ 220.00
48563 Customized 40GBASE-LR4L QSFP+ 1310nm 2km Transceiver US$ 340.00
48564 Customized 40GBASE-LR4 QSFP+ 1310nm 10km Transceiver US$ 340.00
48565 Customized 40GBASE-PLR4 QSFP+ 1310nm 10km Transceiver US$ 380.00
48566 Customized 40GBASE-ER4 QSFP+ 1310nm 40km Transceiver US$ 1,500.00
50004 Customized 10GBASE-LR SFP+ 1310nm 10km DOM Transceiver US$ 34.00
34959 8 Fibers Single Mode 12 Strands MTP-LC Harness Cable US$ 29.00

Spending Less for up to 80km 10G to 40G Connection

Have you ever felt puzzled about whether the 10G to 40G connection can be extended to 80 km? Here you’ll find the answer is yes. How to deploy 80km 10G to 40G connection? You should add the extra equipment, including two DWDM Mux Demux, two WDM transponder OEO (Optical-Electrical-Optical) repeaters and several DWDM SFP+ modules, to your network.

In order to make a smooth 80km 10G to 40G migration, we should add the WDM transponder OEO repeater into the 10G to 40G link. It can not only act as fiber repeater for long distance transmission, but also CWDM/DWDM optical wavelength converter. When the 10G signals pass through the WDM transponder OEO repeater, it will be converted into several DWDM singals. Then you should use the DWDM Mux Demux to multiplex, transmit and demultiplex them. And finally another WDM transponder OEO repeater is required to convert the DWDM singals into 10G signals again. Hence, you can finally achieve the up to 80km 10G to 40G connection. As for the equipment the network requires, you can also order them from FS.COM with good prices.

Product ID Description Price
65909 16 Channels C25-C40 Dual Fiber DWDM Mux Demux US$ 1,100.00
30515 4 Channels Multi-Rate WDM Converter (Transponder) US$ 820.00
64426 Customized C25-C40 10G DWDM SFP+ 80km Transceiver US$ 420.00


FS.COM is an ideal fiber optical manufacturer that offers very cost effective solutions for 10G to 40G connection. These solution can support not only the short 10G to 40G migration at lengths up to 400 m, but also the long migration with reach 1km, 10km or even up to 40km. Moreover, if you want to extend the 10G to 40G connection up to 80 km, you can order the extra equipment like DWDM Mux Demux, WDM transponder OEO repeaters and DWDM SFP+ modules from FS.COM with good price. All the equipment mentioned above have been tested to assure 100% compatibility.

Dual-Fiber or Single-Fiber CWDM Mux Demux for Higher Capacity Need?

What would you do if your network capacity can not meet your requirement? Will you put more fibers or update your system? In fact, these two methods are not very recommendable. Why? As your fiber cabling infrastructure is limited for adding fibers and high cost is required for upgrading system, these two methods are unworkable or too expensive. Under this condition, using a pair of CWDM Mux Demux to build a CWDM system with higher capacity is highly recommended. The CWDM Mux Demux is regarded as a key component for a CWDM system, as shown below. It can be simply divided into two types, dual-fiber and single-fiber CWDM Mux Demux. To meet the higher capacity need of your system, this post will mainly introduce the basic knowledge of the dual-fiber and single-fiber CWDM Mux Demux and guide you find a suitable fiber optic Mux Demux for building your CWDM system.

CWDM Mux Demux for Connecting Cisco Nexus 9396PX and FS S5850-3252Q

Dual-Fiber CWDM Mux Demux

Dual-Fiber CWDM Mux Demux is a passive device multiplexing and demultiplexing the wavelengths for expanding network capacity, which must work in pairs for bidirectional transmission over dual fiber. It enables up to 18 channels for transmitting and receiving 18 kinds of signals, with the wavelengths from 1270 nm to 1610 nm. The CWDM transceiver inserted into the fiber optic Mux port should have the same wavelength as that of Mux port to finish the signal transmission. For instance, the two reliable 4 channel CWDM Mux Demux showed below use four wavelengths, 1510 nm, 1530 nm, 1550 nm and 1570 nm, their corresponding CWDM transceivers also features the same wavelengths.

Dual-Fiber CWDM Mux Demux

When the connection above works, the left 4 channel dual-fiber CWDM Mux Demux uses 1510 nm, 1530 nm, 1550 nm and 1570 nm for transmitting 4 kinds of signals through the first fiber, while the right 4 channel dual-fiber CWDM Mux Demux features 1510 nm, 1530 nm, 1550 nm and 1570 nm for receiving the signals. On the other hand, the transmission from the right to left use the same wavelengths to carry another 4 signals through the second fiber, finally achieving the bidirectional signal transmission.

Single-Fiber CWDM Mux Demux

Single-fiber CWDM Mux Demux should be also used in pairs. One multiplexes the several signals, transmits them through a single fiber together, while another one at the opposite side of the fiber demultiplexes the integrated signals. Considering that the single-fiber CWDM Mux Demux transmitting and receiving the integrated signals through the same fiber, the wavelengths for RX and TX of the same port on the Single-fiber CWDM Mux Demux should be different. Hence, if the 4 channel single-fiber CWDM Mux Demux is used for CWDM system, 8 wavelengths are required, the twice time as that of the dual-fiber one.

Single-Fiber CWDM Mux Demux

The working principle of single-fiber CWDM Mux Demux is more complicated, compared to the dual-fiber one. As shown in the figure above, the transmission from the left to right uses 1470 nm, 1510 nm, 1550 nm and 1590 nm to multiplex the signals, transmit them through the single fiber, and using the same four wavelengths to demultiplex the signals, while the opposite transmission carries signals with 1490 nm, 1530 nm, 1570 nm and 1610 nm over the same fiber. As for the wavelength of the transceiver, it should use the same wavelength as TX of the port on the CWDM Mux Demux. For example, when the port of a single-fiber CWDM Mux Demux has 1470 nm for TX and 1490 nm for RX, then a 1470nm CWDM transceiver should be inserted.

Dual-Fiber vs. Single-Fiber CWDM Mux Demux

We always consider whether an item is worth buying according to its performance and cost. In view of the performance, the single-fiber CWDM Mux Demux can carry signals through only one fiber supporting fast speed transmission and saving the fiber resource, while the dual-fiber one requires two fibers for transmission with a higher reliability. Besides, using single-fiber CWDM Mux Demux can be easier to install. In view of the cost, the single-fiber CWDM Mux Demux is much more expensive than the dual-fiber. And the simplex fiber cable also costs higher than duplex fiber cable. Thereby, the whole cost for building single-fiber CWDM system must be much more higher. Like the two sides of the same coin, both the dual-fiber and single-fiber CWDM Mux Demux have their own advantages and disadvantages. Which one you should choose just depends on your system needs and your budget for building the CWDM system.

Why Not Use Raman Amplifier to Extend the CWDM Network Reach?

In comparison with the long-haul DWDM network that uses the thermo-electric coolers to stabilize the laser emissions essential, the CWDM network is a more economical solution that features wider wavelength spacing, allowing the wavelength fluctuation of uncooled directly modulated laser diodes (DMLs). But on the other hand, the CWDM network exists the limitation for the uncooled DMLs’ output power and the additional loss of CWDM Mux Demux and optical add/drop modules. These make the CWDM loss budget limited to < 30 dB and the CWDM reach within 80 km. Moreover, when the insertion loss of the dark fiber is higher than our expectation, a decreasing transmission distance may occur. Hence, here offers the Raman amplifier (see the following figure) to extend the CWDM network reach, as an ideal solution.

Raman Amplifier

What’s Raman Amplifier?

Raman amplifier, also referred to as RA, is a kind of optical fiber amplifier based on Raman gain, which is used for boosting optical signals and finally achieving a longer transmission distance. Different from the erbium-doped fiber amplifier (EDFA) and semiconductor optical amplifier (SOA), the RA intensifies the signals through the nonlinear interaction between the signal and a pump laser within an optical fiber, as shown in the figure below.

Raman amplifier working principle

At present, two kinds of Raman amplifiers are available on the market, the distributed and lumped Raman amplifiers. As for the distributed Raman amplifier (DRA), it uses the optical fiber as the gain medium to multiplex the pump wavelength with signal wavelength, so that the optical signals can be boosted. With regard to the lumped one (LRA), it requires a shorter length of optical fiber for the signal amplification. Both of these two Raman amplifiers are suitable for amplifying CWDM signals and extending the CWDM network reach.

Why Raman Amplifier Is Used for Amplifying CWDM Signals?

As we know, the EDFA and SOA are able to strengthen the CWDM signals. But why it is not recommendable for the CWDM network? In fact, they can not perform as well as the RA in the CWDM network for some limitations, which can be learned from the following figure.

Optical Fiber Amplifier Comparison

The figures above shows various gain bandwidths of these three optical fiber amplifiers for CWDM network, but only the gain bandwidth the RA offers meet the CWDM network demands. To fully serve the CWDM network, the RA usually optimizes the pumping lightwave spectrum to extend the usable optical bandwidth. As for the EDFA, its gain bandwidth can not match well with the channel spacing of the CWDM network requirements. And for the SOA, although it offers the gain bandwidth fit enough for the CWDM network, it is still not suggested for the inherent technical limitations. In details, the SOA has a relatively low saturation power but a high noise figure and polarization sensitivity, compared to other two amplifiers. Hence, the RA is undoubtedly the best choice to strengthen the CWDM signals and lengthen the CWDM network reach.

How Does Raman Amplifier Benefit CWDM Network?

In order to study the benefit of RA for the CWDM network, here offers two sets of research data about the receiver sensitivity, for a bit-error rate (BER) of 10-9 using a pseudo-random bit sequence (PRBS) with a 231-1 word length.

Raman Amplifier Benefits for CWDM Network

From the figure above, we can learn that the first set of data is resulted from the four channel CWDM network without use of the RA, while the second utilizes the RA. In order to check whether the Raman amplifier benefits the CWDM network, we can take the data of 100km CWDM transmission through singlemode fiber (SMF) as an example. The power penalty of the transmission with a RA are separately -34.4 dBm, -34.2 dBm, -33.2 dBm and -32.3 dBm. It is 0.3 dBm better than the power penalty of the transmission without a RA, at least. Except that, we can also learn that the CWDM network with a RA can transmit the signals through the SMF at lengths up to 150m without any repeater stations, while the network without the RA cannot.


The Raman amplifier is an ideal alternative to the repeater in CWDM network, for intensifying the CWDM signals and extending the CWDM network reach. By using the Raman amplifier, the loss budget of the CWDM network can be increased, which finally achieves a longer transmission. Meanwhile, from the view of cost, the RA and the repeater are almost the same, but the repeater stations should cost much more for constructing and maintaining. Moreover, using the RA in the CWDM network can also gain the loss compensation of OADM. Then, why not use Raman amplifier to extend your CWDM network reach?

How to Deploy a Single-Fiber CWDM Network?

Generally, CWDM network designed for expanding the network capacity can be basically divided into two types, dual-fiber and single-fiber CWDM network, according to the optical fiber transmission line. For the dual-fiber CWDM network, its working principle is easy to acquire, which uses the same wavelength for transmitting and receiving each pair of dual-way signals over the duplex fiber cable. However, for the single-fiber CWDM network, the working principle is highly complex that specially works with different wavelengths for transmitting and receiving each pair of dual-way signals over only one fiber. To better understand the single-fiber CWDM network, here will mainly illustrate how does a single-fiber CWDM network work and introduce the components and installation steps for fast deploying a single-fiber CWDM network.

Introduction of Single-Fiber CWDM Network

Single-fiber CWDM network is a kind of WDM network, designed for greatly expanding the network capacity by combining and transmitting several pairs of dual-way signals with different wavelengths over a single fiber, instead of putting more fibers for lager dual-way data transmission need. When the single-fiber CWDM network runs, there are two single-fiber CWDM Mux Demux using two different wavelengths for each pair of dual-way transmission. In details, if the single-fiber CWDM Mux Demux has four channels for dual-way data transmission, then eight different wavelengths divided into four pairs are required for the four channels, as shown in the figure below. To make a comparison, a 4 channel dual-fiber CWDM Mux Demux only needs four different wavelengths for the dual-way transmission.

 4 Channel CWDM Network

From the figure above, we can learn that a 4 channel CWDM network needs two reliable 4 channel CWDM Mux Demux connected by a single fiber and four pairs of CWDM transceivers with eight different wavelengths connected to the CWDM Mux Demux, achieving the dual-way transmission. Obviously, each port of the two CWDM Mux Demux for the same channel has the complete reversed TX and RX. Just taking the first channel as example, the first port of the CWDM Mux Demux on the left side uses 1470nm for TX and 1490nm for RX, while the first port on the right side uses 1490nm for TX and 1470nm for RX, reversely. Hence, each pair of dual-way signals with two different wavelengths will be smoothly transmitted and received. To better understand how does the single fiber CWDM network work, the following table also lists the four pairs of wavelengths for the TX and RX ports of the two CWDM Mux Demux, which are also totally reversed.

TX and RX for Single-Fiber CWDM Mux Demux

Basic Components for a Single-Fiber CWDM Network

When deploy the single-fiber CWDM network, we should prepare two single-fiber CWDM Mux Demux, two switches, a rack-mount chassis, several pairs of CWDM transceivers and singlemode simplex patch cables that are the basic and essential components for a single-fiber CWDM network. The two switches separately act as the Local unit and Remote unit for the CWDM network, while the CWDM Mux Demux is the main unit of the network that should be fixed and held on the rack-mount chassis and then connected to the switch. To finish the connection between the CWDM Mux Demux and switch, we should insert the CWDM transceivers into the ports of CWDM Mux Demux and use the singlemode simplex patch cables to connect CWDM transceivers with the switch.

Basic Components for a Single-Fiber CWDM Network

Steps for Single-Fiber CWDM Network Deployment

To fast deploy a single-fiber CWDM network, here offers the step by step installation procedure.

Step A: Install the rack-mount chassis in a standard 19-inch cabinet or rack.

Step B: Align the single-fiber CWDM Mux Demux with the chassis shelf, slightly push it to the shelf cavity. And tighten the captive screws once the CWDM Mux Demux is totally inserted.

Step C: Plug the CWDM transceivers into the switch. And also, connect these CWDM transceivers to the corresponding ports on CWDM Mux Demux according to the wavelengths of the TX and RX, with the use of singlemode simplex patch cable.

Step D: Utilize the singlemode simplex patch cable to connect the two CWDM Mux Demux and test the performance of the whole single-fiber CWDM network.

Installation Steps for Single-Fiber CWDM Network


Single-fiber CWDM network is a cost-effective and easy-to-deploy solution that can not only take full use of the available fiber bandwidth in your network but also greatly expand your network capacity. If you are hesitating over upgrading your system for bigger capacity, buy CWDM multi-channel Mux/Demux, CWDM transceivers and other basic components to deploy the single-fiber CWDM network would be a better choice for you.

10G DWDM Network for Economically Expanding Capacity

It can’t be denied that for most users, the capacity and transmission data rate their 10G networks offer sufficiently meet their needs at present. However, for some users, their 10G networks are capacity-hungry that requires more and more fiber optical cables installed for carrying large data. Considering that the available fiber infrastructure is limited, the method of putting more cables would be infeasible or unsuitable once the infrastructure no longer fulfill the growing requirements. Is there any economical solution to solve this issue, except upgrading the network that would cost a lot? The answer is yes. In order to create new capacity at a relatively low price, WDM technology is come up with that enables virtual fibers to carry more data. Since WDM technology has been a cost effective solution to face the capacity-hungry issue, here will offer the economical DWDM SFP+ transceiver and DWDM Mux Demux solutions for you to build the 10G DWDM network, which enables bigger capacity to meet your network needs.

DWDM SFP+ Transceiver

The DWDM SFP+ transceiver is an enhanced version of DWDM SFP transceiver that can transmit signals at 10Gbps–the max data rate, mostly deployed in the dark fiber project in combination with the DWDM Mux Demux. Like other kinds of SFP+ transceivers, it is also compliant to the SFP+ MSA (multi-source agreement), designed for building 10G Ethernet network. However, the working principle of DWDM SFP+ transceiver is much more complicated than that of common SFP+ transceiver due to the DWDM technology.

DWDM SFP+ transceiver

Generally, the DWDM SFP+ transceiver has a specific tuned laser offering various wavelengths with pre-defined “colors” which are defined in the DWDM ITU grid. The colors of the wavelengths are named in channels and the wavelengths are around 1550nm. Its channels are commonly from 17 to 61 and the spacing between channels is always about 0.8nm. In fiber optical network, the 100GHz C-Band with 0.8nm DWDM SFP+ transceiver is the most commonly used one, while transceivers with other spectrum bands like 50GHz with 0.4nm spacing DWDM SFP+ transceiver are also popular with users.

According to the transmission distance, the DWDM SFP+ transceiver can be divided into two types. One is the DWDM-SFP10G-40 with an optical power budget of 15dB, and the other is the DWDM-SFP10G-80 with an optical power budget of 23dB. As we know, the bigger the optical power budget is, the longer the transceiver will support the 10G network. Hence, the DWDM-SFP10G-40 can transmit 10G signals at lengths up to 40 km, but the DWDM-SFP10G-80 is able to support the same network with a longer distance, 80 km. What should be paid attention to is that the transmission distance can be also affected by the quality and type of the DWDM Mux Demux, the quality and length of the fiber, and other factors.

DWDM Mux Demux

The DWDM Mux Demux is a commonly used type of fiber optical multiplexer designed for creating virtual fibers to carry larger data, which consists of a multiplexer on one end for combining the optical signals with different wavelengths into an integrated signal and a de-multiplexer on the other end for separating the integrated signal into several ones. During its working process, it carries the integrated optical signals together on a single fiber, which means the capacity is expanded to some extent. In most applications, the electricity is not required in its working process because the DWDM Mux Demux are passive.

Unlike the CWDM Mux Demux with 20nm channel spacing, the DWDM Mux Demux has a denser channel spacing, usually 0.8nm, working from the 1530 to 1570nm band. It is designed for long transmission, which is more expensive than CWDM Mux Demux used for short transmission. Meanwhile, it also commonly used the 100 GHz C-band DWDM technique like the DWDM transceiver. As for its classification, there are basically two types according to line type, dual fiber and single fiber DWDM Mux Demux, and six types according to the number of the channels, 4, 8, 16, 40, 44 and 96 channels DWDM Mux Demux. All these types of DWDM Mux Demux are available at FS.COM with ideal prices. To better understand the DWDM Mux Demux, here offers a figure of a stable 8 channel DWDM Mux Demux for your reference.

8 channel DWDM Mux Demux


Taking the cost issue into consideration, deploying a 10G DWDM network is much more economical than upgrading your network from 10G to 40G/100G which almost requires changing out all the electronics in your network. The 10G DWDM network makes full use of DWDM technology to expand the network capacity, which creates virtual fibers to support more data signals. If your 10G network is also capacity-hungry, you are highly suggested to deploy 10G DWDM network to make new capacity. As for the related components the 10G DWDM network needs like transceiver and Mux Demux, you can easily find them at FS.COM. For instance, FS.COM offers the DWDM SFP+ transceivers compatible with almost every brand, including Cisco, Juniper, Brocade, Huawei, Arista, HP and Dell, which have been tested to assure 100% compatibility.

Things You Should Know to Deploy 100G Ethernet Network

Although the 10G and 40G Ethernet network still occupy the majority of fiber market at present, it is predicted that more and more users would deploy 100G Ethernet network in the following years for higher capacity and faster transmission data rate, and the 100G cabling network would finally make the 10G and 40G cabling network obsolete. Is there any evidence to support this prediction? Why to replace 10G and 40G cabling network and how to deploy the 100G cabling network? Does this statement take the cost issue into consideration since the 100G products like QSFP28 transceiver and QSFP28 breakout cable are much more expensive than the 10G and 40G products? Let’s talk about these topics and find the most cost effective way to deploy the 100G cabling network.

Why We Deploy 100G Cabling Network?

With the fast development of fiber technology, the capacity and transmission data rate that the 10G and 40G networks offer gradually can’t meet our needs and the Ethernet network is still driven to satisfy the increasing requirements of faster and easier access to larger volumes of data. Under this trend, the 100G network is come up with that enables unsurpassed bandwidth but can be only available at a high price. As the 100G technology is gradually matured, the cost for 100G network deployment is reduced a lot. Hence, more and more users would like to deploy the 100G network for bigger bandwidth, even it would still cost higher than 10G and 40G network deployment.

Which Transceiver Is the Best for Deploying 100G Network?

Before designing the 100G cabling network, we should choose the most proper 100G fiber transceiver to greatly ensure the performance of the network. Since there are four common kinds of 100G fiber transceivers–CFP, CFP2, CFP4 and QSFP28 transceiver available on the market, let’s study the basic knowledge of these 100G transceivers and discuss which one is the best choice for the 100G network deployment.

CFP transceiver is the first version of 100G transceiver which is published after the establishment of certification for the first 100G standard for Ethernet networks. The letter “C” means 100G, while the letters “FP” stand for Form factor Pluggable, just like the “FP” in the word SFP. In order to support the 100G network, it features very huge size which is much larger than 40G QSFP+ transceiver. Meanwhile, most of the CFP transceivers double the power consumption per bit and are ten times more expensive for per bit increased. All these shortcomings hinder the popularity of CFP transceiver and make the CFP2 and CFP4 transceiver published successively.

The CFP2 and CFP4 transceiver has no any improvement in the aspects like density, power consumption and cost, but be only advanced in the size aspect. From the following figure, you can learn that the size of the CFP family become more and more smaller. However, due to the high power consumption and cost, using CFP family to deploy 100G network still can’t meet the network requirement. Under this condition, experts put forward the QSFP28 transceiver solution which is much smaller and more economic than CFP family.


In contrast to the CFP family, QSFP28 transceiver is a better choice that offers four 25-Gbps lanes, totally achieving the whole 100G network. With use of this kind of 100G transceiver, the 100G network can be deployed as easy as the 10G and 40G network. Moreover, it completely eliminates the costly gearbox found in CFP and CFP2, while highly increasing density and decreasing power and price per bit. Hence, among all the 100G transceivers, the QSFP28 transceiver is the first choice for deploying 100G network, which should be considered as the most economical transceiver solution.

Which 100G Cabling Solution Should Be Selected?

After choosing the best 100G transceiver solution, it is also necessary to design the 100G cabling network. At present, there are basically two 100G cabling solutions. One is the direct cabling solution usually working with the QSFP28 cable, and the other is the breakout cabling solution that always uses the QSFP28 breakout cable. Considering that each solution has its own connection method and works with different fiber or copper cable, which one should be selected depends on the practical application.

QSFP28 Cable for 100G Direct Cabling and QSFP28 Breakout Cable for 100G Breakout Cabling

As for the 100G direct cabling solution, it always uses the 100GBase-SR4 QSFP28 transceiver to finish short distance transmission, and 100GBASE-LR4 QSFP28 transceiver for long transmission. In short transmission case, the 100GBase-SR4 QSFP28 transceiver can support the 100G network through OM3 12 fiber multimode MTP cable at lengths up to 70 m, and 100 m through OM4 12 fiber multimode MTP cable. It can also work with the 100G QSFP28 to QSFP28 passive direct attach cable (DAC) for up to 5m transmission and with the 100G QSFP28 to QSFP28 active direct attach cable (AOC) for up to 10m transmission. While in the long transmission case, 100GBASE-LR4 QSFP28 transceiver enables the 100G network up to 10 km on single-mode LC patch cable. If much longer transmission distance is required, you are highly suggested to choose the 100GBASE-ER4 CFP transceiver that can transmit the 100G signal at lengths up to 40 km.

As for the breakout cabling solution, the connection method is very different from the previous one, which usually use the QSFP28 breakout cable to connect one QSFP28 transceiver on one side and four SFP28 transceivers on the opposite side. This kind of 100G cabling solution enables higher port bandwidth, density and configurability at a low cost and reduces power consumption in data centers. Besides, the QSFP28 breakout cables used for 100G breakout cabling can be simply divided into two types, QSFP28 to 4SFP28 DACs and AOCs. Both of the two kinds of QSFP28 breakout cables feature four individual 25G duplex cables to achieve 100G connections, similar to the 40G QSFP+ breakout cable that has four individual 10G duplex cables.


With the gradual mature of 100G Ethernet technology, the cost issue is not the obstacle for the popularization of 100G Ethernet network any more. If your network has a very low transmission speed and the capacity it offers can’t face your need, then you are recommendable to upgrade your network from 10G/40G to 100G, for faster and easier access to larger volumes of data. As for the transceiver used for 100G connection, the QSFP28 is the fist choice as the most cost effective solution at present. As for the 100G network cabling, the direct cabling for 100G to 100G connection and the breakout cabling for 100G to 4×25G connection are good solutions for 100G network deployment. Which one should be selected just depends on the practical application.