| 摘要 |
PURPOSE:To make a laser beam with narrow spectral line width to be stably emitted, by adjusting the phase of the return laser beam in the boundary surface between a laser section and a waveguide section to a desired value by both the effects of diffraction gratings and the control of waveguide length. CONSTITUTION:A waveguide section comproses diffraction gratings 2B, 2C which are formed inside both the end surfaces of a waveguide 3 guiding the incident laser beam from a laser section, an index varying region N of the waveguide located between the diffraction gratings, an electrode 12 for controlling waveguide length which is disposed over the index varying region N in order to inject carriers by which the waveguide length is effectively controlled. According to this structure, the laser beam generated in the laser section is made to enter into the waveguide section, and the incident laser beam is then reflected by the end surfaces of the waveguide section to return the laser beam to the laser section. Therefore, when the spectral line width of the laser beam is contracted, the phase of the return laser beam in the boundary surface between the laser section and the waveguide section can be adjusted to the desired value owing to both the effects of the diffraction gratings and the control of the waveguide length. |
