Coarse Wavelength Division Multiplexer Capacity

CWDM systems typically support up to 18 channels per fiber, each spaced 20 nm apart, covering wavelengths from 1270 nm to 1610 nm.

Channel Capacity and Wavelength Range

Coarse Wavelength Division Multiplexing (CWDM) allows multiple optical signals to be transmitted over a single fiber by assigning each signal a distinct wavelength, or "lambda".

Standard CWD

M systems use wide channel spacing of 20 nm, which reduces the need for precise, temperature-stabilized lasers and allows for cost-effective transceivers. The nominal wavelength range spans 1270 nm to 1610 nm, enabling up to 18 channels on a single fiber when using modern OS2 fibers that overcome water peak limitations.

Data Rates

Each CWD

M channel typically supports 1 to 3. 125 Gbit/s, making the total fiber capacity dependent on the number of channels deployed. For example, an 18-channel CWDM system could theoretically provide up to 56.

25 Gbit/s aggregate bandwidth using standard transceivers. System Design ConsiderationsCWDM uses multiplexers and demultiplexers to combine and separate wavelengths on a single fiber. The system is bi-directional, allowing signals to travel in both directions on the same fiber.

Unlike DWD

M, CWDM does not support wideband optical amplification, which limits the transmission distance to several tens of kilometers without repeaters or amplifiers.

CWD

M is particularly suitable for metropolitan networks, enterprise backhauls, and FTTx applications, where cost-effective expansion of existing fiber infrastructure is needed. Comparison with DWDMWhile CWDM supports fewer channels with wider spacing, DWDM systems can support 40, 80, or more channels with narrow spacing (50–100 GHz), enabling much higher total capacity for long-haul networks.

CWD

M is preferred for shorter distances and lower-cost deployments, whereas DWDM is used for high-capacity backbone networks. In summary, CWDM provides up to 18 channels per fiber, each spaced 20 nm apart, with typical per-channel data rates of 1–3. 125 Gbit/s, making it a cost-effective solution for metropolitan and enterprise optical networks.