For WDM/SCM systems using direct modulation, we evaluated the required performances of key optical devices ; laser diodes(LDs), opeical filters, and EDFAs. Focusing on chirping of LDs, we clarified the method to decide the required values of FWHM of optical filters and RIN of EDFAs. In the case of the 32WDM/310ch-SCM system, it is needed that RIN of EDFAs is less than 136.5dB/Hz, and FWHM of optical filters is between 0.35nm and 0.65nm, when the product of FM efficiency and difference between bias current and threshold current of a LD is less than 10GHz. Developed key optical deveces satisfied all their requirements.
