DWDM / CWDM Grid
Convert between frequency (THz), wavelength (nm) and ITU channel, and list the channels of a band at the chosen spacing. Based on ITU-T G.694.1 and G.694.2.
Channels of the band
| n | Frequency (THz) | λ (nm) |
|---|
CWDM grid · ITU-T G.694.2 (18 channels)
| Channel | λ (nm) | Frequency (THz) | Band |
|---|
How it works · the ITU grid
1. DWDM (G.694.1): the grid is
anchored at 193.1 THz. Each channel is
f = 193.1 + n·(spacing/1000), with spacing in GHz and
n an integer (positive or negative).
2. The wavelength comes from
λ = c / f, with c = 299792.458 nm·THz. So
193.1 THz equals 1552.524 nm.
3. The C band spans
~191.35–196.10 THz (1530–1565 nm): at
100 GHz it fits about 48 channels;
at 50 GHz, twice as many.
4. CWDM (G.694.2) uses not
frequency but 18 fixed wavelengths from
1271 to 1611 nm, every 20 nm.
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