| 摘要 |
PURPOSE:To eliminate the incidence onto a photodetector for direct monitoring of the light of the different wavelength and to correctly control the output of a semiconductor laser by arranging an interference filter at the emitting window of the semiconductor laser. CONSTITUTION:An interference filter 29 to transmit selectively only the oscillation wavelength of a semiconductor laser 24 is arranged at an emitting window 23 of a semiconductor laser 3. Consequently, the interference filter 29 transmits only the wavelength of the light irradiated from a laser chip 24 in the internal part of the semiconductor laser 3, does not transmit the light of other wavelength, and therefore, it is prevented that the light of other wavelength is made incident on a photodetector 26 for monitoring in the internal part of the semiconductor laser 3 as leaking light and stray light. Thus, even when plural semiconductor lasers 3 different in wavelength are used simultaneously at the same optical system, plural semiconductor lasers 3 can be individually and correctly output-controlled. |
