A method includes obtaining a semiconductor wafer having an orientation in a plane; depositing one or more masks to a semiconductor wafer, wherein each mask is configured to cover a portion of the semiconductor wafer, and wherein each mask includes a perimeter having multiple sides that are substantially aligned along a preferred crystal direction relative to the orientation that provides reduced or enhanced growth enhancement at edges of the substantially aligned sides; and performing Selective Area Epitaxy (SAE) growth on a surface of the semiconductor wafer, wherein the one or more masks inhibit the SAE growth over the associated portion.

A mode-locked semiconductor laser capable of changing the spacing between the carrier frequencies of its output comb. In an example embodiment, the mode-locked semiconductor laser is implemented as a hybrid solid-state device comprising a III-V semiconductor chip and a silicon chip attached to one another to form a laser cavity. The III-V semiconductor chip includes a gain medium configured to generate light in response to being electrically and/or optically pumped. The silicon chip includes a plurality of optical waveguides arranged to provide multiple optical paths of different effective lengths for the light generated in the laser cavity. Different optical paths can be controllably selected, using one or more optical switches connected between the optical waveguides, to change the effective optical length of the laser cavity and, as a result, the output-comb frequency spacing. In some embodiments, the output-comb frequency spacing can be changeable at least by a factor of 1.5.

An optoelectronic lighting device includes an optoelectronic semiconductor chip including a top side and an underside opposite the top side, wherein a semiconductor layer sequence is formed between the top side and the underside, the semiconductor layer sequence includes an active zone that generates electromagnetic radiation, and a barrier for a bonding material flowing on account of cohesive bonding of the semiconductor chip to a carrier is formed at one of the top side and the underside.

A semiconductor laser including an active zone and a waveguide, wherein the active zone includes an active layer configured to generate electromagnetic radiation during operation of the semiconductor laser, the waveguide is configured to guide the electromagnetic radiation generated during operation of the semiconductor laser within the semiconductor laser, the waveguide includes a subregion formed from a compound semiconductor material, wherein a proportion of a material of the compound semiconductor material gradually increases in the entire subregion along the vertical direction toward the active zone so that a refractive index of the subregion gradually decreases toward the active zone, and the proportion is an aluminum proportion or a phosphorus proportion.

Examples disclosed herein relate to multi-wavelength semiconductor lasers. In some examples disclosed herein, a multi-wavelength semiconductor laser may include a silicon-on-insulator (SOI) substrate and a quantum dot (QD) layer above the SOI substrate. The QD layer may include and active gain region and may have at least one angled junction at one end of the QD layer. The SOI substrate may include a waveguide in an upper silicon layer and a mode converter to facilitate optical coupling of a lasing mode to the waveguide.

A QCL may include a substrate, an emitting facet, and semiconductor layers adjacent the substrate and defining an active region. The active region may have a longitudinal axis canted at an oblique angle to the emitting facet of the substrate. The QCL may include an optical grating being adjacent the active region and configured to emit one of a CW laser output or a pulsed laser output through the emitting facet of substrate.

An optical apparatus comprises a semiconductor substrate and an optical waveguide emitter. The optical waveguide emitter comprises an input waveguide section extending from a facet of the semiconductor substrate, a turning waveguide section optically coupled with the input waveguide section, and an output waveguide section extending to the same facet and optically coupled with the turning waveguide section. One or more of the input waveguide section, the turning waveguide section, and the output waveguide section comprises an optically active region.

A germanium waveguide is formed from a P-type silicon substrate that is coated with a heavily-doped N-type germanium layer and a first N-type doped silicon layer. Trenches are etched into the silicon substrate to form a stack of a substrate strip, a germanium strip, and a first silicon strip. This structure is then coated with a silicon nitride layer.

A waveguide structure including a waveguide having a thermally controllable section, and a method of manufacturing the structure. The waveguide structure comprises a plurality of layers. The layers comprise, in order: a substrate (306), a sacrificial layer (305), a lower cladding layer (303), a waveguide core layer (302), and an upper cladding layer (301). The lower cladding layer, waveguide core layer, and upper cladding layer form the waveguide, the waveguide has a waveguide core. The waveguide structure has a continuous via (307) passing through the upper cladding layer, waveguide core layer, and lower cladding layer and running parallel to the waveguide ridge (304) along substantially the whole length of the thermally controllable section. The waveguide structure also has a thermally insulating region (308) in the sacrificial layer extending at least from the via to beyond the waveguide ridge along the whole length of the thermally controllable section. The sacrificial layer comprises a sacrificial material outside of the thermally insulating region, and a thermally insulating gap (308) or thermally insulating material separating the lower cladding layer and substrate inside the thermally insulating region. The structure is manufactured by providing a wet etch to the sacrificial layer through the via in order to remove material from at least the thermally insulating region.

Methods, systems, and apparatus, including a laser including a layer having first and second regions, the first region including a void; a mirror section provided on the layer, the mirror section including a waveguide core, at least part of the waveguide core is provided over at least a portion of the void; a first grating provided on the waveguide core; a first cladding layer provided between the layer and the waveguide core and supported by the second region of the layer; a second cladding layer provided on the waveguide core; and a heat source configured to change a temperature of at least one of the waveguide core and the grating, where an optical mode propagating in the waveguide core of the mirror section does not incur substantial loss due to interaction with portions of the mirror section above and below the waveguide core.