Wavelength Division Multiplexing (WDM) is a vital technology used to transmit multiple signals over a single optical fiber. There are two primary types of WDM: Coarse Wave Division Multiplexing (CWDM) and Dense Wave Division Multiplexing (DWDM). CWDM uses a wider range of wavelengths, typically spaced by 20 nanometers. This leads to a simpler syst