Abstract
Recent progress on semiconductor lasers for Wavelength Division Multiplexed (WDM) optical communication is introduced. WDM systems require the accurate wavelength setting. The lasing wavelength is determined by many factors of stripe width, active layer thickness and composition, etc. New devices are required for WDM networking. Wavelength tuning and semiconductor laser amplifier are newly required. Wavelength tuning is needed in the network for superimposing the signal with the appropriate wavelength. Semiconductor laser amplifiers are for compensating losses. Array lasers are needed for compact light sources with many wavelengths and the substitute of tunable lasers. Array lasers, tunable lasers and semiconductor gate switches with amplifier are discussed here.
