Normal WDM (sometimes called BWDM) uses the two normal wavelengths 1310 and 1550 nm on one fiber. Coarse WDM provides up to 16 channels across multiple transmission windows of silica. are then discussed with special focus on WDM Mux/demultiplexer (DeMux). The chapter concludes by highligh sy d components have been changing the landscape of communication as such. The constant push for. 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.