Patent ID: 6985505

Claim:
A semiconductor laser diode comprising: a semiconductor substrate; a semiconductor layered body which is formed on the semiconductor substrate and has at least an active region; a first electrode provided on the semiconductor substrate at a side opposite to a side on which the semiconductor layered body is formed; and a second electrode provided at the side of the semiconductor layered body, wherein the semiconductor layered body has semiconductor layered portion on an upper region with respect to the active region thereof, the semiconductor layered portion being in the shape of a ridge having a length thereof in a light-propagating direction and a cavity under the ridge, the cavity being a laser cavity defined by reflection facets, the second electrode on the semiconductor layered portion side contacts an upper face of the semiconductor layered portion, the second electrode on the semiconductor layered body side includes a plurality of conductor layers, at least the most outer one of the conductor layers has a length thereof in the light-propagating direction shorter than the length of the semiconductor layered portion, the plurality of conductor layers constituting the electrode on the semiconductor layered body side include a first conductor layer region which is close to the semiconductor layered body and a second conductor layer region which is formed on the first conductor layer region, the second conductor layer region has a portion having a thickness thinner than that of a central portion thereof in the vicinity of a reflection facet of the laser cavity, an edge of the thinner portion at the reflection facet side is located at a position identical with that of an edge of the first conductor layer region, and an edge of the thicker portion at the reflection facet side is recessed inward from a position of the edge of the first conductor layer region.