DWDM Technology for High Speed Optical Communications

The ever-increasing demand for applications in internet, digital cable TV, e-mail, data transmission etc. has forced the utilization of the available more than two THz transmission bandwidth of single-mode optical fiber at low loss and low dispersion window of 1550 nm. Most of the optical communication systems in use today range from 2.5 Gbit/s, 10 Gbit/s and 40 Gbit/s while 160 Gbit/s and 480 Gb/s systems are in developmental stages. The main stumbling block to achieve this high bit-rate is the limitation of the electronic components used in the receiver and transmitting systems as well as the dispersing in the fibers. In wavelength division multiplexing (WDM) several channels at different wavelengths are multiplexed and transmitted simultaneously over a single fiber. The bit rate in each channel is lower to meet the electronic limitations but overall bit rate is quite high due to large number of channels. As the separation between successive channels becomes very small (1 nm to 0.8 nm) it is customary to use the term Dense Wavelength Division Multiplexing (DWDM) instead of WDM. This paper presents the concept of WDM/DWDM, component requirements, system characterization, current status and future developments. Index Terms – DWDM, Optical Communication, Dispersion, TDM, Multiplexing, Demultiplexing, Four wave mixing, WDM standards.