| 摘要 |
PURPOSE:To enable the reduction in vertical mode width of a semiconductor laser and the stabilization of the oscillation wavelength without lowering the intensity of signal light and with miniaturization and simplicity by a method wherein the reflected light from an optical fiber end surface is enabled to be subjected to feedback to one end surface side of laser beam emission so as to become coincident with the phase of light in the semiconductor laser. CONSTITUTION:A forward output light 6 of the semiconductor laser 1 is used as the signal light, and a backward output light 7 is made incident to optical fibers 3-5, so that the lights can be monitored in a photo receptor 8. The tip of a shorter optical fiber 3 is made to have lens effect in convex, and the light incident to the fiber 3 is fed back to the laser 1 by reflection on a reflection plane 10. In this case, making the phase of a light fed back to the laser 1 the same as the phase of a light in the laser 1 is enabled by slight variation of the temperature of the laser 1 or the bias current. This manner can reduce the vertical mode width. The light received in the photo receptor 8 is guided to an outside APC or an AFC circuit, and the wavelength can be controlled by varying the bias current of the laser 1. |
