Patent ID: 7738520

Claim:
A semiconductor laser comprising: a gain region having wavelength selectivity; a propagating region optically coupled to said gain region, the propagating region having a length, the propagating region also having an effective refractive index whose temperature dependence differs from that of said gain region, and having no wavelength selectivity; and a reflection region for reflecting light propagated through said propagating region with high reflectivity, wherein said gain region comprises a diffraction grating formed by periodic perturbation with at least one of real and imaginary parts of a complex refractive index and the coupling coefficient of the diffraction grating of said gain region is greater than 300 cm −1 , so that said gain region and said reflection region form a cavity for laser oscillation within an extended stop bandwidth, the cavity having an effective length, the wavelength of the laser oscillation being determined by an optical phase determined by the effective cavity length and the length of the propagation region while a center wavelength of the stop band changes over temperature due to temperature dependence of the effective refractive index of the gain region.