Patent ID: 7099357

Claim:
A wavelength-tunable laser apparatus comprising: a semiconductor substrate; a Fabry-Perot laser formed on the semiconductor substrate, the laser having a plurality of longitudinal modes; and a planar lightwave circuit formed on the semiconductor substrate, the circuit including a waveguide disposed on the substrate so that light outputted from the laser is coupled to the waveguide, the circuit further including a clad surrounding the waveguide, with a grating being carved into a portion of the waveguide, the grating reflecting a plurality of light beams of different wavelengths, the Fabry-Perot laser being wavelength-locked by one of the plural reflected light beams; wherein a wavelength interval between the plurality of longitudinal modes of Fabry-Perot laser and a wavelength interval between the plurality of light beams are different than each other, and operating temperature of the Fabry-Perot laser is controlled for wavelength tuning by wavelength-locking of another one of the plural reflected light beams.