| 摘要 |
PURPOSE:To reduce the effects caused by the reflected light of a laser beam, and to eliminate mode distribution noises which are generated at the time of transmission by an optical fiber and noises which are generated in case a plural number of longitudinal modes exist by a method wherein a double hetero structure is buried-in with other different semiconductor material and a periodic roughness is formed on the interface of a semiconductor layer wherein the exudation of the laser beam exists. CONSTITUTION:On the (100) surface of an N type InP substrate 1 are grown an N type InP layer 2 (Te doping, impurity concentration 3X10<18>/cm<3>) in a depth of 1mum, an In0.73Ga0.27As0.63P0.27 layer 3 (undoping, impurity concentration 5X10<16>/cm<3>) in a depth of 0.1mum and a P type In0.78Ga0.22As0.5P0.5 4 (0.4mum) according to an liquid-phase eiptaxial growth method. The semiconductor layer 4 is needed the conditions that the refractive index thereof is slightly smaller than that of the laser active layer 3 and is larger than that of a clad layer. the semiconductor layer 4 is formed in such a way that light oscillated from a laser is exuded in the layer 4 and is propagated in a transversal fundamental mode. As a result, the breaking limit by light in the laser active layer is never exceeded and a large output is obtained. Besides, a diffraction grating is formed on the semiconductor layer. For this reason, distortion is not generated in the active layer, thereby enabling to prolong the lifetime of the laser. |
