| 摘要 |
PURPOSE:To prevent the effect by reflection noises on a laser by contriving to make the vertical mode of the laser single by a method wherein the center of the position of laser oscillation and the center of the position of reflected light are put in proximity without coincidence, in the feedback of the laser emitted light. CONSTITUTION:The emitted light 6 from the active layer 5 of a semiconductor laser chip 1 is made parallel by means of a collimating lens 2, reflected by a reflection optical element 3 such as a mirror and a diffraction grating, turned to a converged light 7 by means of the collimator 2, and then fed back to the resonance end surface 9 of the laser chip 1. The semiconductor laser device is brought to a strong vertical single mode by converging a reflected light region 11 to an oscillation region 10 at this surface 9, and thus putting the luminous center and the reflected light center in arrangement in the neighborhood without coincidence. The emitted light 8 from the other end of the laser chip 1 is introduced to an optical fiber 4 and then made as the light source for optical communication, and accordingly the effect of reflection noises on the laser is prevented. |
