Patent ID: 8488644

Claim:
A semiconductor laser element, comprising: a first electrode and a second electrode to apply a current to the semiconductor laser element; and a first reflecting mirror and a second reflecting mirror to make up an optical resonator, wherein the resonator includes: an active layer, a current confinement layer confining a flow of the current between the first electrode and the second electrode, the current confinement layer including a first region to allow the flow of the current and a second region to confine the flow of the current, a first semiconductor layer having a first doping concentration formed at a side opposite to the active layer across the current confinement layer, and a second semiconductor layer having a second doping concentration higher than the first doping concentration formed between the first semiconductor layer and the current confinement layer, the first semiconductor layer includes a third region that faces the first region and a fourth region that faces the second region, the first electrode is provided to contact at least a part of a surface of the first semiconductor layer in the fourth region, the first semiconductor layer has a diffusion portion where a component of the first electrode or at least a part of components of the first electrode diffuses into the first semiconductor layer, the second semiconductor layer contacts the diffusion portion and extends from a region contacting the diffusion portion to a portion facing the first region, the second semiconductor layer is positioned at a node of a standing wave formed in the resonator at a time of laser oscillation of the semiconductor laser element, the diffusion portion extends fully through the first semiconductor layer in a thickness direction thereof, and extends partially, but not fully, through the second semiconductor layer in a thickness direction thereof, and both of a side surface of the diffusion portion and a bottom surface of the diffusion portion contact the second semiconductor layer, the bottom surface of the diffusion portion having a larger area than the side surface of the diffusion portion.