Coarse Wavelength-Division Multiplexing (CWDM) is an economical technique to save fiber resources through transmitting multiple wavelengths on one optic fiber. Especially, CWDM has the benefit of low cost becuase of its uncooled modulating lazer which only consumes 0.5w power. The cost of CWDM system only takes up 30% of the DWDM expense. Thus, CWDM is suitable for the application in short distance, high bandwidth and areas with dense access points. However, the disadvantage of CWDM is that its supportable wavelengths are limited, usually for five or six different optic wavelengths between 1270nm and 1610nm with a 20nm interval.