| 摘要 |
PROBLEM TO BE SOLVED: To make a semiconductor laser have the necessary variable width of its wavelength for a multi-wavelength communication, etc., and prevent the width of its wavelength-spectrum line from increasing when varying its wavelength, by making different from each other the extents of temperature rises of its optical waveguide, both in one portion of the region with a means for selecting its wavelength through its injection current and in the other region with no means. SOLUTION: A diffraction grating 16 is formed on the interface between a lower optical waveguide 12 and a lower optical confinement layer 11. There are provided alternately in the direction of a resonator a first region whose current width is intactly equal to the width of a stripe-form optical waveguide and a second region whose current width is narrowed. While the current injecting portion of the first region is 2 μm in its stripe width and 100 μm in its length, the current injecting portion of the second region is limited to 0.5 μm in its width and 100 μm in its length owing to an InP layer 15 with a high resistance. The area of a current flowing in the second region becomes one-fourth of the one in the first region to make the heat generation quantity of the second region four times as large as the one of the first region. Therefore, the temperature of the optical waveguide is made high due to its injection current to make shift to long-wavelength side the Bragg wavelength determined by the pitch of the diffraction grating 16. |
