CWDM systems supporting 2 to 16wavelengths are commercially available today. These systems are anticipated to scale to 16 wavelengths in the 1,290-1,610-nm wavelength region. Today, most CWDM systems are based on 20-nm channel spacing from 1,470 to 1,610 nm, with some development occurring in the 1,300-nm window. Wavelengths in the 1,400-nm region suffer higher optical signal loss due to the attenuation peak caused by residual water present in most of the installed fiber. While this additional loss can limit system performance for longer links, it is not a major obstacle to CWDM deployment in most metro access spans.

CWDM system with 20 nm channel spacing (G.694.2), bumber of channels 4, 8, 12 and 16(18) wavelength applications for Unidirectional or bidirectional (single fibre) applications, speed per CWDM channels is up to to 10G Gbit/s per wavelength using CWDM XFP, CWDM SFP+, CWDM XENPAK, CWDM SFP+