Semiconductor laser device and optical fiber amplifier

摘要

A semiconductor laser device comprises an optical fiber (20) having an optical fiber grating (30) formed therein, a semiconductor laser (11) having an active layer (41) with a single quantum well, for emitting laser light, and a coupling optical system (15) for coupling the laser light emitted out of the semiconductor laser into the optical fiber. The coupling optical system can include a narrow-band filter (17) for adjusting an incident angle of the laser light emitted out of the semiconductor laser. The optical fiber grating (30) can have a reflection bandwidth wider than or substantially equal to a 3dB bandwidth of the gain of the semiconductor laser or a spectrum full width at half maximum of the laser light of the semiconductor laser.