What is the base frequency and channel spacing specied by ITU for DWDM?

The International Telecommunication Union (ITU) specifies the base frequency for Dense Wavelength Division Multiplexing (DWDM) as 193.1 THz, corresponding to a wavelength of approximately 1550 nm. The channel spacing defined by ITU for DWDM systems is typically 50 GHz or 100 GHz, depending on the specific standard being used. This spacing allows for efficient use of the optical spectrum while minimizing interference between channels.