Patent ID: 7620093
Filing Date: 2009-11-17
Classification: H01S

Abstract:
1. A semiconductor laser comprising: a first diffractive grating region that has a plurality of segments combined to each other, that has a gain, and that has a first discrete peaks of a reflection spectrum, each of the segment having a diffractive grating and a space region; and a second diffractive grating region that is combined to the first diffractive grating region, that has a plurality of segments combined to each other, and that has a second discrete peaks of a reflection spectrum, each of the segments having a diffractive grating and a space region, a pitch of the second diffractive grating being substantially the same as that of the diffractive grating of the first diffractive grating region, a wavelength interval of the second discrete peaks being different from that of the first discrete peaks, a part of a given peak of the first discrete peaks is overlapped with a part of a given peak of the second discrete peaks in a case where a relationship between the given peak of the first discrete peaks and the given peak of the second discrete peaks changes, wherein: a first segment located in the first diffractive grating region or the second diffractive grating region has an optical length shorter or longer than the other segments of the first diffractive grating region and the second diffractive grating region by odd multiple of half of the pitch of the diffractive grating of the first diffractive grating region, and the first segment is one of two segments of the first diffractive grating region or one of two segments of the second diffractive grating region that are on the boundary side between the first diffractive grating region and the second diffractive grating region.