JPS6433986A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To make the oscillation only of fundamental transversal mode controllable while longitudinal multi-mode is maintained, and obtain a device wherein the oscillation threshold value is low and the stable oscillation is enabled up to a high output level, by using effective light confinement effect by making the angle between the side surface of a rib-type optical waveguide in a semiconductor laser of specific structure and a junction plane set in a specific range. CONSTITUTION:A part of a clad layer 205 right above the active layer 204 of a double heterojunction type semiconductor laser in which AlxGa1-xAs is used, is eliminated. In the vicinity of a resonator end surface, the width of a refractive index waveguide and the width of current injection are made nearly equal, to constitute a refractive index waveguide structure. In the other region, the width of the refractive index waveguide is made wider than the width of current injection, and a gain waveguide structure is made up. A rib type optical waveguide is arranged as follows; the length of the refractive index waveguide region of the light emission side is 10-500mum, the length of the refractive index waveguide region of a monitor side is equal to or less than 500mum, the length of the gain waveguide region is 10-500mum, the width of the refractive index waveguide region is 1-10mum, the width of the gain waveguide regin is more than or equal to 5mum, and the current injection width is 1-10mum. An AlGaAs layer 209 is buried in the side part of the above optical waveguide to make the angle between the side surface of the rib-type optical waveguide and the junction surface 50-120 deg..