Tag Archives: DWDM

Getting to Know the DWDM Transceivers in DWDM Systems

To keep pace with the rapid growth of Internet traffic, service providers have been seeking to improve fiber capacity and wavelength spectrum efficiency in their networks. In response to this situation, DWDM technology is emerging. DWDW is an optical multiplexing technique for increasing the bandwidth of existing fiber networks. DWDM transceivers are important parts of DWDM network, which provide high-capacity and long-distance transmissions. Let’s take a closer look together.

dwdm transceivers

What are DWDM and DWDM Transceiver?

DWDM refers to dense wavelength division multiplexing, which is a technology that gathers data signals from different sources, enables them to share a single optical fiber pair while the separation of data streams is ensured. It supports up to 80 simultaneous wavelength channels, with each of the channels only 0.8nm apart. The technology creates multiple virtual fibers thus multiplies the capacity of the physical fiber cable. It is applied to increase bandwidth over existing fiber networks and transmit data for longer distances.

DWDM transceiver is a kind of fiber optic transceiver with its own features and functions. It is designed for single-mode fiber transmission and operates at a nominal DWDM wavelength from 1528.38 to 1563.86 nm (Channel 17 to Channel 61) as specified by the ITU-T. Like other transceivers, it converts the electrical signal to optical signal and vice versa. The transceiver can support up to 10 Gbps and span a distance up to 120 km, which makes itself stand out in high-capacity and long-distance transmissions.

Types of DWDM Transceivers for DWDM Networks

DWDM transceivers are available in different types, which can support transmission rate from 155 Mbit/s to 10 Gbit/s. Here are the common types of DWDM transceivers classified based on data rate, form factor and fixed or tunable wavelength.

From the Perspective of Data Rate

In the case of data rate, DWDM transceiver usually can be divided into two types: 1G   DWDM transceiver and 10G DWDM transceiver. 1G DWDM transceiver includes DWDM SFP transceiver. 10G DWDM transceiver can be further divided into DWDM SFP+ transceiver, DWDM X2 transceiver, DWDM XFP transceiver and DWDM XENPAK transceiver. DWDM SFP transceiver provides a signal rate range from 100 Mbps to 2.5 Gbps, usually used as part of a DWDM optical network to provide high-capacity bandwidth. DWDM SFP+/X2/XFP/XENPAK transceivers support 10-Gigabit data rates from 9.9G to 11.25G (LAN, WAN, and OTU2/OTU2e) which are applied in different applications.

From the Perspective of Form Factor

In terms of form factor, DWDM transceiver can be classified into DWDM SFP transceiver, DWDM SFP+ transceiver, DWDM X2 transceiver, DWDM XFP transceiver and DWDM XENPAK transceiver. Among those transceivers, DWDM SFP and SFP+ transceivers are the most commonly used ones, based on the SFP form factor which is an MSA standard build. DWDM X2 transceiver is based on the X2 form factor, designed for high speed data transmission for data center networking. It’s an ideal choice for data communications and telecommunications switches and routers. DWDM XFP transceiver is based on the XFP form factor which is also an MSA standard build. DWDM XENPAK transceiver is SC duplex receptacle module and is designed for backbone Ethernet transmission systems, which is the first 10GbE transceiver that supports DWDM. It can support 32 different channels for transmission distance up to 200 km with the aid of EDFAs.

From the Perspective of Fixed or Tunable Wavelength

Considering fixed or tunable wavelength, DWDM transceiver can be divided into fixed wavelength DWDM transceiver and DWDM tunable transceiver. Fixed wavelength DWDM transceiver, as the name implies, the wavelength is fixed. It can only transmit a certain number of wavelength, regular fixed wavelength transceiver transmits wavelength at 1310nm and 1550nm for 10G data transmission applications. The Tunable DWDM transceiver is a unique product which enables you to set the channel or “color” that the laser emits. Typically these tunable optics are for the C-Band 50GHz. Around 88 different channels can be set with intervals of 0.4nm. Tunable transceivers are typically used as “spare-optics”, in case of emergency.


In DWDM systems, a large number of DWDM transceivers with different wavelengths, data rates and form factors are required to satisfy network flexibility in optical network. Now that you know all the types of DWDM transceivers, you can compare them with each other and find the one you need. FS.COM provides a variety of transceivers including those mentioned above. High-quality and cost-effective products, intimate service only at FS.COM. You won’t want to miss it.

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An Overview of DWDM Technology and DWDM System Components
How to Enhance the Optical Signals for a Long DWDM System?

Effective CWDM & DWDM Mux/Demux Solutions for WDM System

Wavelength division multiplexing (WDM) system is designed for high capacity communications. It is now frequently used as a method to merge multiple optical signals with different wavelengths onto a single fiber. There are two divisions of WDM system: coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM). Using WDM can enhance the effectiveness of bandwidth in fiber optic communications. The WDM Mux/Demux has a number of communication channels, and matches with a certain frequency. Wavelengths are separated to different receivers at the destination. Mux/Demux module is an important assembly using WDM technology. This article will introduce some effective CWDM and DWDM Mux/Demux solutions for WDM system.

CWDM Mux/Demux & DWDM Mux/Demux
CWDM Mux/Demux

CWDM Mux/Demux is a flexible network solution for WDM optical networks. At most 18 full-duplex wavelengths can be added over a single fiber trunk which greatly alleviates fiber exhaustion. With low insertion loss and high stability, CWDM Mux/Demux is applied to many operations, such as CATV links, WDM systems, test and measurement, metro and access networks, FTTH networks, etc. The deployment of CWDM Mux/Demux is transparent and clear. Its compact form factor enables a much easier manipulation. Only coarse wavelengths can be transmitted over the fiber which reduces the WDM system cost.

Three kinds of CWDM Mux/Demux are widely used in the application. They are 1RU 19″ rack chassis CWDM Mux/Demux, half 19″/1RU CWDM Mux/Demux and splice/pigtailed CWDM Mux/Demux. CWDM Mux/Demux in 19 inch rack mount package is often used for CWDM, EPON and CATV network. Half 19″/1RU CWDM Mux/Demux is packed in LGX box using thing film coating and non-flux metal bonding micro optics packaging. Splice/pigtailed CWDM Mux/Demux is packed in the ABS box package based on standard thin film filter (TFF) technology.

DWDM Mux/Demux

DWDM Mux/Demux conveys optical signals in a more dense wavelength. It is especially used for long distance transmission where wavelengths are highly-packed together. The maximum delivered wavelengths can reach up to 48 channels in 100GHz grid (0.8nm) and 96 channels in 50GHz grid (0.4nm). DWDM Mux/Demux uses a reliable passive WDM technology that achieves low insertion loss. And it provides a solution for adding WDM technology to any existing network device. Applications like point-to-point DWDM fiber optimization, linear add/drop DWDM fiber optimization, external optical monitoring are typically using DWDM Mux/Demux module.

Likewise, 1RU 19″ rack chassis DWDM Mux/Demux, Half 19″/1RU DWDM Mux/Demux and splice/pigtailed DWDM Mux/Demux are three divisions of DWDM Mux/Demux modules. The first type is in 19 inch rack mount package used for long-haul transmission over C-band range of wavelengths. The second one is in LGX package used for PDH, SDH/SONET, Ethernet services transmission. The last one is in ABS box package and its pigtails are labeled with wavelengths.

Effective CWDM Mux/Demux & DWDM Mux/Demux Solutions

18-CH CWDM Mux/Demux is a highly recommended 1RU rack-mount CWDM Mux/Demux that combines 18 CWDM sources on a single fiber. The insertion loss is below 4.9 dB. Moreover, it has a monitor port that enables maintenance without ceasing the operation.


40-CH DWDM Mux/Demux has 40 channels. As a DWDM Mux/Demux module with high density, low-loss and independent 1RU rack mount package, the best utilization of this device is to employ it for high density applications over long-haul transmission. It multiplexes and demultiplexes 40 DWDM wavelengths with 100 GHz in a ring or point-point network. It is a highly cost-effective DWDM Mux/Demux module.



To improve the efficiency of network transmission, WDM technology is often deployed in the devices. 18-CH CWDM Mux/Demux and 40-CH DWDM Mux/Demux are now recommended as the most cost-effective WDM solutions with expanded fiber capabilities. Hope you can choose and use them wisely.

Guide to Optical Amplifier

In pursuit of high transmission capacity, people have been tried many ways. For example, they pave more cables or use the TDM (time domain multiplexer) to improve the transmission capacity. But in these traditional ways, signals could become weaker in power through the fiber link. And the further they are transmitted, the weaker the signals will be until they can not be detected. With the advanced of technology, optical amplifier which is a better solution to improve the transmission capacity came around. It can strengthen the attenuated signals and even can bring them back to the original level. And now it is mainly applied in DWDM technology so that DWDM technology can support long-haul transmission.

Working Principles of Optical Amplifier

Optical amplifier is a device that can amplifier optical signals directly, which does not need to convert optical signals to electric signals first. And we will take the common kind for example to explain its working principles, namely, EDFA (erbium doped fiber amplifier). Optical fiber is often doped with rare-earth elements, such as erbium or praseodymium which can be pumped into a excited state by pump laser. When input signals pass by the fiber, they will stimulate the excited atoms of erbium so that the atoms of erbium can release their energy in the form of emitted light photons. It is the emitted light photons who has the same phase and wavelength with input signals that amplify the optical signals.

Working Principles of EDFA

Working Principles of EDFA

Types of Optical Amplifier

Optical amplifier can be divided into three types now. They are the doped fiber amplifier, the semiconductor optical amplifier and the Raman amplifier. Next we will introduce each of amplifiers.

Doped fiber amplifier has several types according to the kinds of rare earth elements. Erbium-doped fiber amplifier is the most common one. Just like we said before, its amplifying medium is the fiber doped with erbium elements. The amplified light’s wavelength is around 1550 nm, which suffers minimum attenuation. And this amplifier has low noise and is applied in the long-haul telecommunication networks. The second is semiconductor optical amplifier whose gain medium is undoped InGaAsP. Compared with EDFA, it is less expensive and more suitable for local networks. Raman amplifier’s gain medium is undoped optical fiber. It is made with Raman scattering effect which is an important non-linear effect. By the early part of 2000s, it is used for long-haul (typically between 300 and 800 km) or ultra-long-haul (typically longer than 800 km) fiber-optics transmission system. And this amplifier has been commercialized these days, with sold at a high price.

The advent of optical amplifier is a great success in optical fiber communication technology. At present, it has been become a basic device in modern telecommunication networks and brings much effectiveness to economy and society, which presents a good trend for the market prospect.

WDM Overview

With the development of the computers, mobile phones and some other things, there is an increasing eagerness for more traffic volume of telecommunication. So WDM, with more bandwidth and faster data transmission rate, comes into being.

WDM is a technology to send multiple different wavelength lasers on a single optical fiber. As shown in the picture below, there are different signals coming from different channels. when through the multiplexer, they can be transmitted on a single fiber without obstructed by each other at a high speed. And then, when they are through the demultiplexer, they will be allocated into different channels. The multiplexer and the demultiplexer are the most important parts in WDM systems, just like transmitter and receiver. When signals are transmitted to the network medium on the fiber links, they will be amplified. And after through the network medium, the signals will still be amplified on the fiber links untill they are received by the receiver.

WDM-wavelength division multiplexing

Currently, there are two types of it in the market. CWDM, short for coarse wavelength division multiplexing, is a low-cost WDM transmission technology. Another type is DWDM, namely, dense wavelength division multiplexing. The primary difference between them is the channel spacing. The channel spacing of CWDM is wider than DWDM, so that the number of its channels on the same link could be reduced relatively. As a result, its optical interface components does not need to be precise as same as DWDM.

Now the technology of WDM is widely used in optical networks. Why can it be so widely used? The reasons is closely linked to its features. First, it has Super capacity transmission technology. The transmission capacity can be up to 300-400 Gbit/s or even larger. Second, it can save fiber resources. No matter how many SDH subsystems there are, the whole reuse system only needs a pair of optical fiber. Third, it can work with EDFA that strengthens and restores the attenuated signals in the long-distance transmission, so that it can reduce the cost. Forth, it can improve the reliability of the system. Because most WDM systems are the photoelectric devices which have high reliability. This is a guarantee for the system reliability.

As the optical communication technology progressed further, WDM will be developed in some aspects. In terms of DWDM, Something still needs to be improved such as cost, so that more customers can adopt it.