CWDM Small Form Factor Pluggable (SFP) optical transceiver is a convenient and cost-effective solution for the adoption of Gigabit Ethernet and Fibre Channel in data center and metropolitan-area access networks. There are 18 center wavelengths available from 1270nm to 1610nm, in 20nm spacing. These wavelengths are compliant to the ITU G.694 CWDM standard. Normal transmission distance like 40km and 80km, all these modules can come with digital diagnostics monitoring (DDM) functions and are very cost-effective.