A semiconductor laser device is provided with a semiconductor layer including an active layer and a plurality of cladding layers sandwiching the active layer. The active layer includes a stripe-shaped active region, a pair of first refractive index regions and a pair of second refractive index regions sandwiching the active layer and the pair of first refractive index regions. When is the laser oscillation wavelength, n.sub.a is the effective refractive index of the active region, n.sub.c is the effective refractive index of the first refractive index regions, n.sub.t is the effective refractive index of the second refractive index regions, w is the width of the active region, and m is a positive integer, the semiconductor laser device satisfies n.sub.a>n.sub.t>n.sub.c, and the conditions of equations (5), (8) and (9).

The invention is directed to a hybrid, vertical current injection electro-optical device, comprising an active region and one or more current blocking layers. The active region includes a stack of III-V semiconductor gain materials designed for optical amplification. The gain materials of the stack are stacked along a stacking direction z, which is perpendicular to a main plane of the stack. The one or more current blocking layers extend perpendicularly to the stacking direction z and laterally on opposite sides of the active region. The one or more current blocking layers each have an effective refractive index n.sub.1 that is matched to the effective refractive index n of the active region, i.e., n.sub.1=fn, with f[0.95; 1.05]. The invention is further directed to a silicon photonics chip comprising such an electro-optical device.

A semiconductor laser device of the present disclosure includes: a first-conductivity-type cladding layer, a first-conductivity-type-side optical guide layer, an active layer, a second-conductivity-type-side optical guide layer, a second-conductivity-type cladding layer, and a second-conductivity-type contact layer, laminated above a first-conductivity-type semiconductor substrate; and a resonator having a length L.sub.c. The resonator includes a current confinement region having a length L.sub.f and a current injection region having a length L.sub.cL.sub.f. The current confinement region includes a ridge inner region, ridge outer regions provided on both sides thereof and having current non-injection structures, and cladding regions which are provided on both sides thereof and in which at least the contact layer and the cladding layer are removed. The current injection region includes a ridge region and the cladding regions provided on both sides thereof.

A semiconductor laser device is provided with a semiconductor layer including an active layer and a plurality of cladding layers sandwiching the active layer. The active layer includes a stripe-shaped active region, a pair of first refractive index regions and a pair of second refractive index regions sandwiching the active layer and the pair of first refractive index regions. When ? is the laser oscillation wavelength, n.sub.a is the effective refractive index of the active region, n.sub.c is the effective refractive index of the first refractive index regions, n.sub.t is the effective refractive index of the second refractive index regions, w is the width of the active region, and m is a positive integer, the semiconductor laser device satisfies n.sub.a>n.sub.t>n.sub.c, and the conditions of equations (5), (8) and (9).

The invention is directed to a hybrid, vertical current injection electro-optical device, comprising an active region and one or more current blocking layers. The active region includes a stack of III-V semiconductor gain materials designed for optical amplification. The gain materials of the stack are stacked along a stacking direction z, which is perpendicular to a main plane of the stack. The one or more current blocking layers extend perpendicularly to the stacking direction z and laterally on opposite sides of the active region. The one or more current blocking layers each have an effective refractive index n.sub.1 that is matched to the effective refractive index n of the active region, i.e., n.sub.1=fn, with f [0.95; 1.05]. The invention is further directed to a silicon photonics chip comprising such an electro-optical device.

To provide an optical semiconductor device having excellent long-term reliability, the optical semiconductor device includes: a substrate; a mesa structure provided on the substrate; a semiconductor burial layer provided in contact with two sides of the mesa structure; and an electrode containing Au, which is provided above the semiconductor burial layer. The mesa structure includes a first conductivity type semiconductor layer, a multiple-quantum well layer, and a second conductivity type semiconductor layer, which are stacked in the stated order from a substrate side. The semiconductor burial layer includes a first semi-insulating InP layer provided in contact with side portions of the mesa structure, a first anti-diffusion layer provided in contact with the first semi-insulating InP layer, and a second semi-insulating InP layer provided on the first anti-diffusion layer. The first anti-diffusion layer has an Au diffusion constant that is smaller than that of the first semi-insulating InP layer.

A tunable laser device is described. In one example, the tunable laser device includes an adaptive ring mirror, a gain waveguide, a loop mirror waveguide, and a booster amplifier waveguide. The gain waveguide and the boost amplifier waveguide can be formed in a semiconductor optical amplifier (SOA) region of the tunable laser device, and the adaptive ring mirror and the loop mirror waveguide can be formed in a silicon photonics region of the tunable laser device. The adaptive ring mirror includes a phase shifter optically coupled between a number of MMI couplers. By inducing a phase shift using the phase shifter, the wavelength of the output of the tunable laser device can be altered or adjusted for use in coherent fiber-optic communications, for example, among other applications.

A semiconductor laser element includes a nitride semiconductor layered body defining an optical waveguide, and including a first n-side nitride semiconductor layer having a periodic structure of a refractive index periodically changing along a resonance direction of the optical waveguide, a p-side nitride semiconductor layer, an active layer including one or more well lavers and barrier lavers, the one or more well layers including an n-side well layer located closest to the first n-side nitride semiconductor laver, and the one or more barrier layers including an n-side barrier layer disposed between the n-side well layer and the first n-side nitride semiconductor layer, and a second n-side nitride semiconductor layer disposed between the first n-side nitride semiconductor layer and the active layer. The second n-side nitride semiconductor layer includes In and Ga. A thickness of the second n-side nitride semiconductor layer is greater than a thickness of the n-side barrier layer.

A photonic crystal surface-emitting laser includes a substrate, an n-type cladding layer, an active layer, an index matching layer and a photonic crystal structure. The n-type cladding layer is disposed over the substrate. The active layer is disposed over the n-type cladding layer. The index matching layer is disposed over the n-type cladding layer and is arranged around the active layer. The index matching layer is electrically insulating, and an effective refractive index of the index matching layer is substantially identical to an effective refractive index of the active layer. The photonic crystal structure is disposed over the active layer and the index matching layer.

An optical device includes an active layer disposed over a semiconductor substrate, a diffraction grating disposed over the active layer, a clad layer partly disposed over the diffraction grating, at least one first burying material layer disposed beside side surfaces of end portions of the clad layer over the diffraction grating, and at least one second burying material layer disposed beside side surfaces of a center portion of the clad layer over the diffraction grating. A refractive index of the at least one first burying material layer is different from a refractive index of the at least are second burying material layer.