WDM MUX DEMUX Complete Guide: CWDM vs DWDM Multiplexing
Wavelength Division Multiplexing (WDM) technology allows multiple optical signals to be transmitted over a single fiber by using different wavelengths. MUX and DEMUX devices combine and separate these wavelengths.
How WDM Works
Each data channel is transmitted on a unique wavelength (color) of light. The MUX combines them at the transmitting end, and the DEMUX separates them at the receiving end. This multiplies fiber capacity without laying new cables.
CWDM vs DWDM
CWDM (Coarse WDM) uses 18 channels spaced 20nm apart (1270-1610nm). Lower cost but limited to about 80km reach. DWDM (Dense WDM) uses 40+ channels spaced 0.8nm apart (C-band). Higher capacity and longer reach (1000km+ with amplification).
MUX/DEMUX Types
Thin-film filter (TFF) types are common for CWDM. Arrayed waveguide grating (AWG) types for DWDM. Add-drop multiplexers (OADM) allow selective wavelength add/drop at intermediate sites.
Selection Guide
Choose CWDM for links under 80km. Choose DWDM for long-haul or high-channel-count applications. Consider insertion loss, channel spacing, and package type.
