Patent ID: 7173757

Claim:
A broad-band light source comprising: a semiconductor optical amplifier including an active layer serving as a gain area, an under-cladding layer and an over-cladding layer formed on the lower and the upper surfaces of the active layer, respectively, and antireflection layers formed at both ends of the active layer; a reflector disposed for reflecting light outputted from the semiconductor optical amplifier so that the reflected light is inputted back to the active layer, the reflector configured to minimize a gain ripple of the semiconductor optical amplifier; and an optical waveguide disposed between the semiconductor optical amplifier and the reflector, and configured to achieve an optical coupling between the semiconductor optical amplifier and the reflector, wherein the length of the optical waveguide is at least twice as much as a coherence length of an amplified spontaneous emission of the light generated from the semiconductor optical amplifier.