How does WDM work?

A WDM system uses a multiplexer at the transmitter to join the several signals together and a demultiplexer at the receiver to split them apart. There are multiplexer(MUX) and demultiplexer(DEMUX). The main function of MUX is to combine multiple signal wavelengths in one fiber for transmission at the sending end. And the main function of the demultiplexer DEMUX is to separate multiple wavelength signals transmitted in an optical fiber at the receiving end.

The main purpose of wavelength division multiplexing(WDM) is to increase the available bandwidth of the fiber. Therefore, wavelength division multiplexing systems are widely used by telecom companies to expand capacity through WDM without laying more fibers.

CWDM, DWDM, CCWDM, How to choose?

CWDM is sparse wavelength division multiplexer, also known as coarse wavelength division multiplexer. CWDM is being used in cable television networks, where different wavelengths are used for the downstream and upstream signals. In these systems, the wavelengths used are often widely separated.

DWDM is dense wavelength division multiplexer. Dense wavelength division multiplexing (DWDM) refers originally to optical signals multiplexed within the 1550 nm band so as to leverage the capabilities (and cost) of erbium doped fiber amplifiers (EDFAs), which are effective for wavelengths between approximately 1525–1565nm (C band), or 1570–1610nm (L band).

CCWDM is a mini wavelength division multiplexer, which is a mini version of CWDM. A wavelength division multiplexing technology based on TFF (Thin Film Filter), which works in the same way as CWDM. The difference is that CCWDM uses free space technology, its package size is smaller and the insertion loss is lower. It can replace CWDM products in telecom, enterprise networks, PON networks, TV and other applications.

The main advantage of the CWDM system is the low cost. The device cost is mainly manifested in filters and lasers. The wide wavelength spacing of 20nm also makes CWDM the advantage of low specification of the laser and simplified structure of the optical multiplexer/demultiplexer. The simplified structure and high yield will reduce the cost. The increased cost of DWDM is mainly due to the high cost of laser diodes and the cooling laser technology used to maintain wavelength stability.

CWDM, DWDM and CCWDM are kinds of effective methods to solve the increasing bandwidth capacity needs; but they are designed to meet different network needs.

120 channels / 80 channels on C band and 40 on L band

The semi-active CWDM system adopts asymmetric equipment form, which is composed of AU active CWDM equipment, AAU passive CWDM equipment, color optical module at DU side, color optical module at AAU side and network management system. The semi-active CWDM can provide protection and automatic switching mechanism, and support management, operation and maintenance of front-haul network. DU Active CWDM equipment and AAU passive CWDM equipment multiplex several wavelengths for transmission to save fiber resources. The system can support the mixed transmission of 4G / 5G services at the same time to realize the unified front-haul transmission of 4G / 5G.

This solution solves the network management monitoring problem of 5G front-haul passive WDM equipment carrier network solution. It features low construction cost, network management, line protection function, convenient and flexible for system maintenance, and it is also very helpful for operators to divide the maintenance interface. The network management monitoring platform includes the network management unit, which supports visual network management. Through the function card, it can intuitively detect the receiving and emitting status of each line, realize the functions of fault diagnosis accurate positioning, alarm display, alarm statistics, alarm processing, etc., through optical line protection card realize the 1+1 link protection, real-time monitoring of main and spare fiber power, automatic protection switching and other protection function, dual power supply, optional AC/DC power, high redundancy.

Reference from glsunmalldotcom

WDM classification is based on channel spacing between two wavelengths * channel spacing greater than 200GHZ is called as CWDM * channel spacing greater than 100GHZ is called as WDM * channel spacing lesser than 100GHZ is called as DWDM * channel spacing lesser than 25GHZ is called as UDWDM 100GHZ = 0.8nm WDM classification is based on channel spacing between two wavelengths * channel spacing greater than 200GHZ is called as CWDM * channel spacing greater than 100GHZ is called as WDM * channel spacing lesser than 100GHZ is called as DWDM * channel spacing lesser than 25GHZ is called as UDWDM 100GHZ = 0.8nm

In physical science, a electronic device may be a device that selects one in every of many analog or digital input signals and forwards the chosen input into one line. A electronic device of 2 or N number inputs has n choose lines, that ar wont to choose that input line to send to the output. Multiplexers ar principally wont to increase quantity of knowledge that may be sent over the network among an explicit amount of your time and information measure.

In fiber optic networking, a multiplexer contains many types such as CWDM multiplexer, DWDM multiplexer and Video multiplexer / Audio multiplexer / Data multiplexer, etc.. (all these multiplexers can be found in FiberStore with pictures)