Wavelength division multiplexing is used at which wavelengths

WDM systems typically use wavelengths in the 1260–1675 nm range, with CWDM around 1470–1610 nm and DWDM primarily in the 1525–1610 nm range.

Wavelength Ranges

Coarse Wavelength Division Multiplexing (CWDM) uses a relatively wide channel spacing, typically 20 nm, and operates over wavelengths roughly from 1470 nm to 1610 nm. This wider spacing allows for simpler, uncooled lasers and is suitable for short- to medium-distance applications such as metro networks or enterprise links . Dense Wavelength Division Multiplexing (DWDM) uses much tighter channel spacing, often 0.4 nm (50 GHz) or 0.8 nm (100 GHz), enabling a higher number of channels. DWDM typically operates in the C-band (1525–1565 nm) and L-band (1570–1610 nm), which coincide with the low-loss window of optical fibers and the amplification range of Erbium-Doped Fiber Amplifiers (EDFAs), . Modern DWDM systems can support over 160 channels on a single fiber, making them ideal for long-haul and high-capacity networks .

Optical Fiber Considerations

The choice of these wavelengths is influenced by fiber attenuation and amplifier compatibility. The 1550 nm region is preferred because standard single-mode fibers exhibit minimal loss (~0.2 dB/km), and EDFAs efficiently amplify signals in this range, allowing long-distance transmission without frequent regeneration .

Summary

• CWDM: 1470–1610 nm, 20 nm spacing, short- to medium-range networks, uncooled lasers.
• DWDM: 1525–1565 nm (C-band) and 1570–1610 nm (L-band), 0.4–0.8 nm spacing, long-haul and high-capacity networks, requires precise, temperature-stabilized lasers.
• Overall WDM range: 1260–1675 nm, limited by fiber attenuation and amplifier performance . These wavelength selections ensure efficient, high-capacity, and low-loss optical communication across various network scales.