Integrated semiconductor laser element, semiconductor laser module, and optical transmission system

摘要

An integrated semiconductor laser element includes: semiconductor lasers that oscillate at different oscillation wavelengths from one another, each laser oscillating in a single mode; an optical coupler; and a semiconductor optical amplifier. At least one of active layers of the semiconductor lasers and an active layer of the semiconductor optical amplifier have a same thickness and a same composition that is set to have a gain peak wavelength near a center of a wavelength band formed by the oscillation wavelengths. The semiconductor optical amplifier includes: an equal width portion formed on a side of the optical coupler to guide light in a single mode; and an expanded width portion formed on a light output side. The width of the expanded width portion is set according to a total thickness of well layers of the active layer of the semiconductor optical amplifier.