Optical fibre wavelength division multiplexing

An overview is given of wave-length division multiplexing (WDM) as a means of expanding communication capacity and implementing special data techniques in a fiber-optic system. This technology is implemented by adding optical sources of different wavelengths at optical transmitting locations, then mixing (multiplexing) the optical signals and coupling them into an optical fiber where they travel to another location. The optical wavelengths are then separated (demultiplexed) and detected by optical receivers. Fundamentally, a wide band of wavelengths between 0.7 and 1.6 μm exists for WDM applications. Even wider bandwidths will be available with the foreseeable development of infrared fibers. Topics covered include current and future applications of WDM, the current availability of WDM semiconductor laser/transmitters, optical-fiber taps and couplers, wavelength multiplexing/demultiplexing methods, and the use of WDM in local area networks