Different wavelength intervals between CWDM and DWDM
CWDM: wavelength interval ≥20nm, total 18 wavelength of 1270nm~1610nm band with 20nm interval,
DWDM: wavelength interval <10nm, usually using 1528nm~1565nm band with wavelength interval of 200GHz (1.6nm), 100GHz (0.8nm) or 50GHz (0.4nm)
