| 摘要 |
PURPOSE:To obtain a device superior in wavelength characteristic, noise characteristic, or the like by providing a non-reflection coating on one resonator end face of a semiconductor laser and reflecting and diffracting the emitted light from this end face on the principal surface of an optical recording medium to feed back the light to the semiconductor laser and projecting the emitted light from the other resonator end face to a photodetector. CONSTITUTION:A coating 2 of low reflectivity is provided on one resonator end face of a semiconductor laser 1, and the light emitted from this coated resonator end face is reflected on the principal surface of an optical recording medium 3 and is fed back to the semiconductor laser again. The light emitted from the other resonator end face is projected to a photodetector 6 for reception. Consequently, the incident light to the photodetector 6 is changed in accordance with the presence/absence and the condition of feedback of the reflected light from a disk 3. Thus, the intensity of light is read by the photodetector arranged in the vicinity of the exit end and the operation level of the semiconductor laser is adjusted to improve S/N of the photodetector output. |
