WDM is a kind of optical passive component used to unify ordivide the light wavelenghth so that you can transmit several, tensor even wavelength in the same optical carrier channel withdifferent wavelength in the same optical fiber. WDM can be dividedinto optical fiber grating WDM. interference light flitering filmwdm, fused-taper wdm according to the difference in original lightdivision. we mainly use interference light filtering wdm rightnow.