Normal WDM (sometimes called BWDM) uses the two normal wavelengths 1310 and 1550 nm on one fiber. Dense WDM (DWDM) uses the C-Band (1530 nm-1565 nm) transmission window but with denser. 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. To begin with, we assume that we have the element parameters from a known process design kit (PDK). The article explains the fundamental principle and its. 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. This guide delves into the principles, types, applications, and future trends of WDM.