JPS6412593A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To obtain a clear light spot with a low noise and with a basic mode only as an oscillation mode by a method wherein the sides of a rib-shape gain waveguide are filled with II-VI compound semiconductor and the length of the gain waveguide and refractive index waveguides are selected so as to have predetermined relations. CONSTITUTION:An n-type GaAs buffer layer 202, an n-type AlxGa1-xAs layer 203, an AlxGa1-yAs active layer (x>y) 204, a p-type Alz-Ga1-zAs layer (z>y) 205 and a p-type GaAs contact layer 206 are built up on an n-type GaAs substrate 201. The layers 206 and 205 are partially etched by using a mask 207 and covered with a ZnSe layer 209. The layer 209 is etched to have a stripe shape and the layer 206 is exposed and electrodes 210 and 211 are applied. Thus, the sides of a gain waveguide which is formed by making the width of a refractive index waveguide sufficiently wider than the current injection width at the middle part of a resonator are filled with II-VI compound semiconductor and the lengths l1 and l3 along the resonator direction of the refractive index waveguides and the length l2 along the resonator direction of the gain waveguides are so selected as to have relations l1not equal to l2, l2not equal to l3 and 0.5<=l3/(l1+l2)<=10. With this constitution, a laser oscillation with a low noise and showing a clear light spot can be obtained.