Wavelength division multiplexing is divided into two types based on wavelength

Wavelength division multiplexing is divided into two main types based on wavelength: Coarse WDM (CWDM) and Dense WDM (DWDM). Coarse Wavelength Division Multiplexing (CWDM)CWDM is a simpler and more cost-effective form of WDM. It uses widely spaced wavelengths, typically 20 nm apart, covering a spectral range from 1270 nm to 1610 nm.

This wide spacing allows for less precise lasers and optical components, reducing system costs.

CWD

M is generally used for short-range communications, up to about 80 km without amplification, and is suitable for applications where moderate capacity is sufficient.

CWD

M systems typically support fewer than 16 channels per fiber. Dense Wavelength Division Multiplexing (DWDM)DWDM provides tighter wavelength spacing, allowing many more channels on a single fiber, often 40 or more channels within the C-band (1530–1565 nm). This enables high-capacity, long-distance transmission, up to 100 km or more with amplification and dispersion compensation.

DWD

M is more complex and expensive than CWDM but is ideal for backbone networks and high-speed data transmission.

Advanced DWD

M systems can achieve ultra-dense spacing down to 12. 5 GHz, further increasing channel capacity. Key DifferencesFeatureCWDMDWDMWavelength spacingWide (≈20 nm)Narrow (≈0.

8–1. 6 nm, or 50–100 GHz)Number of channelsUp to 1640+ (can exceed 80)Transmission distanceShort to medium (≤80 km)Long (≥100 km with amplification)CostLowerHigherApplicationsMetropolitan networks, cost-sensitive linksInternet backbone, high-capacity long-haul networksBoth CWDM and DWDM combine multiple optical signals onto a single fiber using different wavelengths, maximizing fiber utilization and increasing total data capacity.