ATOP CWDM MUX/DEMUX can combine or separate 18 wavelengths into a single optical fiber. The wavelength interval of each group is 20nm. The device has 4-18 channels with a wide channel bandwidth of 13nm, and the adjacent channel interval is more than 30dB, and the non-adjacent channel interval is more than 40dB. The product has high stability in various environments and is complied with ITU standards.