Wavelength division multiplexing (WDM) is a technique of multiplexing multiple optical carrier signals through a single optical fiber channel by varying the wavelengths of laser lights. WDM allows communication in both the directions in the fiber cable. In WDM, the optical signals from different. 📦 For purchasing, use the RP Photonics Buyer's Guide for wavelength division multiplexing. It provides an expert-curated supplier directory, buyer-focused technical background information, and structured selection criteria to support professional procurement decisions. This allows multiple channels of data to be transmitted simultaneously. These so-called wavelength regions—also known as optical wavelength transmission bands—are essential to modern fiber networks.