Based on this investigation, wavelength division multiplexing (WDM) and OM5 multimode fiber (designed for operation at multiple wavelengths) are leading the way to next generation, short-reach multi- mode networking. Poitras1, Keren Bergman2& Michal Lipson1,3,# 1School of Electrical and Computer Engineering, Cornell University, Ithaca, NY 14853, USA 2Department of. ptical multiplexing techniques, wavelength division multiplexing (WDM). The chapter begins with a quick historical account of the origin of optical communication and its exponential growth following the invention of erbium oped fiber amplifier (EDFA) leading to the widespread adoption of WDM.