What Is DWDM?

Fiber-optic communication network has always been in a state of ongoing evolution. With more challenges of increasing service needs, fiber exhausts, and layered bandwidth managements, solutions have to be provided. Generally, there are two kinds of solutions. One is to increase channel capacity, and the other is to increase the quantity of optical fibers. Wavelength division multiplexing (WDM) is an important innovation to increase channel capacity during this time in optical networks.

WDM is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using specific frequencies of wavelengths within a certain frequency band. There are two types of WDM, coarse WDM and dense WDM. Dense wavelength division multiplexing (DWDM) refers originally to optical signals multiplexed within the 1550nm band so as to leverage the capabilities of erbium doped fiber amplifiers (EDFAs), which can amplify any optical signal in their operating range, regardless of the modulated bit rate. DWDM means that extremely large amounts of data traffic are transmitted over one single strand of optic fiber.

DWDM typically has the capability to transport up to 80 wavelengths in what is known as the Conventional band or C band spectrum, with all 80 channels in the 1550nm region. DWDM takes advantage of the operating window of the Erbium Doped Fiber Amplifier (EDFA) to amplify the optical channels and extend the operating range of the system to over 1500 kilometers. The use of DWDM technology has proven to be the optimal way of combining cost efficient transport with advanced functionality, which can cope with the bandwidth explosion from the access network.

A basic DWDM system contains several components. During the application process, many pieces of DWDM equipment are needed, such as DWDM multiplexer filters, demultiplexer filters, optical add/drop multiplexers (OADMs), optical amplifiers, and transponders, etc. A multiplexer filter combines multiple wavelengths, all within the 1550nm band onto one fiber as a composite signal. A demultiplexer filter separates all of the individual wavelengths of the composite signal out to individual fibers at the receiving end. OADM is designed to only add or drop optical signals with a particular wavelength. Optical amplifiers are used to directly stimulate the photons of the signal with extra energy. Transponders convert optical signals from one incoming wavelength to another outgoing wavelength suitable for DWDM applications. Every piece of DWDM equipment is of its own special value and they are all very important.

DWDM is a technology that puts data from different sources together on an optical fiber, with each signal carried at the same time on its own separate light wavelength. It is a product of scientific and technological progress. The emergence of DWDM is one of the most recent and important phenomena in the development of fiber optic transmission technology.