ASE light source is a high stable, high output power broadband light source. It is widely used for manufacturing and testing of passive components such like fiber grating, DWDM thin film filter, CWDM thin film filter and AWG, as well as isolator and coupler. ASE broadband light source has C band and C+L band two types. The ASE source output spectrum curve could be the nature Er-fiber ASE curve or the flatten ASE curve with the GFF.