Wavelength Division Multiplexing (WDM) is a technique in fiber-optic communication systems that enables multiple optical signals with different wavelengths to be combined, transmitted, and separated over a single optical fiber. This makes it possible to scale capacity cost-effectively by using existing infrastructure more efficiently. Learn when to use WDM, how it works, and how open. 📦 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. Each wavelength (color) transports a signal. WDM allows communication in both the directions in the fiber cable.