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. Two types are available: integrated arrayed waveguide gratings (AWG), offering low cost, compact size, and precise ITU. Wavelength division multiplexers are fundamental to the functioning and performance of integrated photonic circuits, with applications ranging from optical interconnects to sensing and quantum technologies. It can perform additional roles like providing redundancy, supporting advanced topologies, reducing hardware and cost, etc.