An optical semiconductor device includes: a base including a base surface; a mesa protruding from the base surface in a first direction intersecting the base surface and extending along the base surface; an optical waveguide layer provided inside the mesa or provided inside the base so as to have a region at least overlapping with the mesa in the first direction; an electric resistance layer including a first region provided on the mesa, and a first extending portion extending from the first region in a direction intersecting an extending direction of the mesa; and a wiring layer including a second region electrically connected to the electric resistance layer and configured to partially cover the first region, and a second extending portion configured to at least partially cover the first extending portion and extending from the second region in a direction intersecting the extending direction of the mesa.

A semiconductor laser includes: a multi-quantum well layer in a mesa structure; a buried layer comprising a semi-insulating semiconductor, the buried layer being in contact with each of both sides of the mesa structure; a first cladding layer with a first conductivity type, the first cladding layer having a lower refractive index than the multi-quantum well layer; a high refractive index layer configured to not absorb light oscillating in the multi-quantum well layer, the high refractive index layer having a higher refractive index than the first cladding layer; a diffraction grating layer at least partially constituting a diffraction grating capable of diffracting the light oscillating in the multi-quantum well layer, the diffraction grating layer not contacting the high refractive index layer; a substrate with the first conductivity type; and a second cladding layer with a second conductivity type above the multi-quantum well layer.

A surface emitting laser includes a first reflective layer, an active layer provided on the first reflective layer, and a second reflective layer provided on the active layer. The first reflective layer, the active layer, and the second reflective layer form a mesa, and the mesa has an electrically insulating region and an electrically conductive region. The electrically insulating region is positioned at a center portion of the mesa in a surface direction, and the electrically conductive region includes the first reflective layer, the active layer, and the second reflective layer and is positioned outside the electrically insulating region in such a manner as to surround the electrically insulating region.

A laser structure may include a substrate, an active region arranged on the substrate, and a waveguide arranged on the active region. The waveguide may include a first surface and a second surface that join to form a first angle relative to the active region. A material may be deposited on the first surface and the second surface of the waveguide.

In some implementations, a thermally-controlled photonic structure may include a suspended region that is suspended over a substrate; a plurality of bridge elements connected to the suspended region and configured to suspend the suspended region over the substrate, where a plurality of openings are defined between the plurality of bridge elements; and at least one heater element having a modulated width disposed on the suspended region. The at least one heater element having the modulated width may include at least one section of a greater width and at least one section of a lesser width. The at least one section of the greater width may be in alignment with an opening of the plurality of openings and the at least one section of the lesser width may be in alignment with a bridge element of the plurality of bridge elements.

A light emitting device includes: a base having a bottom face and a lateral part surrounding the bottom face and extending upwards from the bottom face, wherein the lateral part comprises a first stepped portion and a second stepped portion facing the first stepped portion; a first semiconductor laser element disposed on the bottom face and located between the first stepped portion and the second stepped portion in a top view, wherein the first semiconductor laser element is configured to emit light towards the second stepped portion; a first wiring region located on the first stepped portion; and one or more first wires, each having a first end that is connected to the first wiring region. At least one of the one or more first wires is electrically connected to the first semiconductor laser element.

A bottom-emitting multijunction VCSEL array includes a first reflector region, a multijunction active region, and a second reflector region. In one aspect, the multijunction VCSEL array is attached to a submount by flip-chip bonding. In another aspect, the multijunction VCSEL array further includes a contact layer formed between the first reflector region and the substrate. The multijunction VCSEL array is attached to a submount by flip-chip bonding.

A quantum-cascade laser element includes: a semiconductor substrate; a semiconductor laminate formed on the semiconductor substrate to include a ridge portion configured to include an active layer having a quantum-cascade structure; an embedding layer including a first portion formed on a side surface of the ridge portion, and a second portion extending from an edge portion of the first portion on a side of the semiconductor substrate along a width direction of the semiconductor substrate; a metal layer formed on a top surface of the ridge portion, on the first portion, and on the second portion; and a dielectric layer disposed between the second portion and the metal layer. The dielectric layer is formed such that a part of the second portion is exposed from the dielectric layer. The metal layer is in contact with the second portion at the part.

A quantum-cascade laser element includes: an embedding layer including a first portion formed on a side surface of a ridge portion, and a second portion extending from an edge portion of the first portion along a width direction of a semiconductor substrate; and a metal layer formed at least on a top surface of the ridge portion and on the first portion. A surface of the first portion has a first inclined surface inclined with respect to the side surface to go away from the side surface as going away from the semiconductor substrate, and a second inclined surface located opposite to the semiconductor substrate with respect to the first inclined surface and inclined with respect to a center line to approach the center line as going away from the semiconductor substrate. The metal layer extends over the first inclined surface and the second inclined surface.

A laser diode drive system configured to output a drive signal to control a voltage provided to a laser diode can include a circuit sensor system configured to output a sensed signal indicative of a drive current of a laser diode, and a temperature sensor configured to output a temperature signal indicative of a temperature of the laser diode or an ambient temperature of the laser diode. The system can include a temperature compensation system configured to output a correction signal based on the temperature signal to compensate for a temperature dependent factor in the sensed signal.