A light emitting element assembly includes: a light emitting element (21); a light emitting element drive unit (30); a first joining member (41) connected to an electrode provided in the light emitting element (21); and a second joining member (42) provided on the light emitting element drive unit (30). In the light emitting element assembly, one of the first joining member (41) and the second joining member (42) includes an alloy material, the other one of the first joining member (41) and the second joining member (42) includes a metallic material, the joining member (the second joining member (42)) including the alloy material includes a first portion (43) and a second portion (44), the joining member (the first joining member (41)) including the metallic material and the first portion (43) are joined to each other, and the second portion (44) is provided on the light emitting element drive unit (30) between the light emitting element (21) and the light emitting element drive unit (30), and is in contact with the light emitting element (21).

A semiconductor laser according to an embodiment of the present disclosure includes a semiconductor stack section. The semiconductor stack section includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, in which the second semiconductor layer is stacked on the first semiconductor layer and includes a ridge having a band shape, and an active layer. The semiconductor stack section further has an impurity region that is at least a portion of a region not facing the ridge and that is located at a position deeper than at least the active layer, in which the impurity region has an impurity concentration of the second conductivity type higher than an impurity concentration of the second conductivity type in a region, of the second semiconductor layer, facing the ridge.

A semiconductor laser according to an embodiment of the present disclosure includes a semiconductor stack section. The semiconductor stack section includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, in which the second semiconductor layer is stacked on the first semiconductor layer and includes a ridge having a band shape, and an active layer. The semiconductor stack section further has an impurity region that is at least a portion of a region not facing the ridge and that is located at a position deeper than at least the active layer, in which the impurity region has an impurity concentration of the second conductivity type higher than an impurity concentration of the second conductivity type in a region, of the second semiconductor layer, facing the ridge.

A semiconductor laser element includes: a first conductivity-type cladding layer; a first guide layer disposed above the first conductivity-type cladding layer; an active layer disposed above the first guide layer; and a second conductivity-type cladding layer disposed above the active layer. A window region is formed in a region of the active layer including part of at least one of the front-side end face or the rear-side end face, the first conductivity-type cladding layer consists of (Al.sub.xGa.sub.1-x).sub.0.5In.sub.0.5P, the first guide layer consists of (Al.sub.yGa.sub.1-y).sub.0.5In.sub.0.5P, and the second conductivity-type cladding layer consists of (Al.sub.zGa.sub.1-z).sub.0.5In.sub.0.5P, where x, y, and z each denote an Al composition ratio, 0<x−y<z−y is satisfied, and D/L>0.03 is satisfied, where L denotes a length of the resonator and D denotes a length of the window region in the first direction.

A semiconductor laser element includes: a first conductivity-type cladding layer; a first guide layer disposed above the first conductivity-type cladding layer; an active layer disposed above the first guide layer; and a second conductivity-type cladding layer disposed above the active layer. A window region is formed in a region of the active layer including part of at least one of the front-side end face or the rear-side end face, the first conductivity-type cladding layer consists of (Al.sub.xGa.sub.1-x).sub.0.5In.sub.0.5P, the first guide layer consists of (Al.sub.yGa.sub.1-y).sub.0.5In.sub.0.5P, and the second conductivity-type cladding layer consists of (Al.sub.zGa.sub.1-z).sub.0.5In.sub.0.5P, where x, y, and z each denote an Al composition ratio, 0<x−y<z−y is satisfied, and D/L>0.03 is satisfied, where L denotes a length of the resonator and D denotes a length of the window region in the first direction.

A laser chip including a plurality of stripes is disclosed, where a laser stripe can be grown with an initial optical gain profile, and its optical gain profile can be shifted by using an intermixing process. In this manner, multiple laser stripes can be formed on the same laser chip from the same epitaxial wafer, where at least one laser stripe can have an optical gain profile shifted relative to another laser stripe. For example, each laser stripe can have a shifted optical gain profile relative to its neighboring laser stripe, thereby each laser stripe can emit light with a different range of wavelengths. The laser chip can emit light across a wide range of wavelengths. Examples of the disclosure further includes different regions of a given laser stripe having different intermixing amounts.

Provided here are: a laser diode section provided on a surface of an n-type InP substrate; a spot-size converter section provided on a surface of the n-type InP substrate, the spot-size converter section being composed of a core layer which causes emitted laser light to propagate therein, a p-type InP cladding layer on a front surface side of the core layer, an n-type InP cladding layer—on a back surface side of the core layer, n-type InP cladding layers provided on the both sides of the core layer, and a p-type InP cladding layer provided on respective surfaces of the p-type InP cladding layer and the first cladding layers; a window region provided on a surface of the n-type InP substrate-that is placed on a front-end side of the core layer; and a monitor PD as a monitor section provided on a surface of the window region.

Provided here are: a laser diode section provided on a surface of an n-type InP substrate; a spot-size converter section provided on a surface of the n-type InP substrate, the spot-size converter section being composed of a core layer which causes emitted laser light to propagate therein, a p-type InP cladding layer on a front surface side of the core layer, an n-type InP cladding layer—on a back surface side of the core layer, n-type InP cladding layers provided on the both sides of the core layer, and a p-type InP cladding layer provided on respective surfaces of the p-type InP cladding layer and the first cladding layers; a window region provided on a surface of the n-type InP substrate-that is placed on a front-end side of the core layer; and a monitor PD as a monitor section provided on a surface of the window region.

A laser chip including a plurality of stripes is disclosed, where a laser stripe can be grown with an initial optical gain profile, and its optical gain profile can be shifted by using an intermixing process. In this manner, multiple laser stripes can be formed on the same laser chip from the same epitaxial wafer, where at least one laser stripe can have an optical gain profile shifted relative to another laser stripe. For example, each laser stripe can have a shifted optical gain profile relative to its neighboring laser stripe, thereby each laser stripe can emit light with a different range of wavelengths. The laser chip can emit light across a wide range of wavelengths. Examples of the disclosure further includes different regions of a given laser stripe having different intermixing amounts.

A semiconductor laser comprises a window structure part including a low resistance active layer formed in end face regions, to have a lower resistance than an active layer located inward with respect to the end face regions. A length between the front end of the contact layer and the front end face is longer by 10 μm or more than a length of a front-end-face side window structure part, and is shorter than a length between the front end face and the rear end of the contact layer. A length between an end of a rear side electrode on the side of the front end face and the front end face is 1.2 times or more a substrate thickness of a substrate, and is shorter than a length between the front end face and an end of the rear side electrode on the side of the rear end face.