In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i. This guide delves into the principles, types, applications, and future trends of WDM. WDM allows communication in both the directions in the fiber cable. Learn when to use WDM, how it works, and how open. Examples include TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access), CDMA (Code Division Multiple Access), and OFDMA (Orthogonal Frequency Division Multiple Access).