| 摘要 |
PURPOSE:To obtain a laser having a single oscillation axis mode by disposing in a multilayer a material having band gap energy larger than the oscillation wavelength lambda on the emitting end surface or its vicinity of a semiconductor laser and deciding the thickness of the layer of i-th from the oscillation mode interval and refractive index. CONSTITUTION:An InP 2 having a thickness of approx. 50mum is placed on the vicinity of the one emitting end of a laser 1 having 1.3mum band of the oscillation wavelength of InGaAsP. The substrate 2 is transparent material for 1.3mum band of laser and operates as a Fabry-Pe rotetalon plate, and the reflectivity repeatedly varies at an interval of DELTAlambda=lambda<2>/2nd with respect to the using wavelength where refractive index is n and the thickness is d. Accordingly, the axial mode interval of the laser is select at DELTAlambda, and the thickness of the plate 2 is selected at d<lambda<2>/2nd, then, the reflectivity difference of the respective oscillation axial mode can be provided. According to this structure, a laser in which the oscillation axial mode is less even at the time of high speed modulation in the single oscillation axial mode and an optimum light source for a large capacity long distance can be obtained. |
