An optical semiconductor device includes: a semiconductor substrate including a first main surface and a second main surface; a stacked body that is formed on the first main surface and includes an active layer and a contact layer arranged on a side opposite to the semiconductor substrate with respect to the active layer; a first electrode in contact with the contact layer; and a second electrode formed on the second main surface. The stacked body includes a light transmitting portion formed by not covering at least part of a surface of the contact layer on a side opposite to the semiconductor substrate with the first electrode. The optical semiconductor device is configured such that a waveguide mode is not formed by current application through the first electrode and the second electrode in a state in which the light transmitting portion is not in optical contact with an external member.

A single-mode micro-laser based on a single whispering gallery mode optical microcavity and a preparation method thereof described includes: preparing a desired single whispering gallery mode optical microcavity doped with rare earth ions or containing a gain material such as quantum dots, wherein an optical microcavity configuration include a micro-disk cavity, a ring-shaped microcavity, and a racetrack-shaped microcavity; a material type include lithium niobate, silicon dioxide, silicon nitride, etc.; preparing an optical fiber cone or an optical waveguide of a required size which can excite high-order modes of the optical microcavity, such as a ridge waveguide and a circular waveguides; and coupling, integrating, and packaging the optical fiber cone or the optical waveguide with the microcavity. A pump light is coupled to the optical fiber cone or the optical waveguide to excite a compound mode with a polygonal configuration.

A light source for a frequency-modulated continuous-wave (FMCW) LiDAR device is formed by a photonic integrated circuit and comprises a substrate and a multilayer structure. Formed in the multilayer structure is a semiconductor laser that is received in a recess etched into the multilayer structure. An optical path between the semiconductor laser and a reflector forms an external cavity for the semiconductor laser. The external cavity includes a variable attenuator causing an attenuation of light guided in the cavity optical waveguide. The external cavity may also or alternatively include an optical phase modulator.

A semiconductor light-emitting device including a light-emitting layer, a first N-type waveguide layer and a plurality of semiconductor layers is provided. The light light-emitting layer has a first side and a second side opposite to the first side. The first N-type waveguide layer is disposed at the first side, and the semiconductor layers are disposed at the second side. The semiconductor layers include at least one P-type semiconductor layer and a plurality of N-type semiconductor layers, and a quantity of the N-type semiconductor layers is more than a quantity of the at least one P-type semiconductor layer.

Structures for response shaping in frequency and time domain, include an optical response shaper and/or a modulator device with multiple injection. The device comprises a resonator having an enclosed geometric structure, for example a ring or racetrack structure, at least two injecting optical waveguides approaching the resonator to define at least two coupling regions between the resonator and the injecting waveguides, and may define at least two Free Spectral Range states. One or both of the coupling regions has a coupling coefficient selected for a predetermined frequency or time response, and the coupling coefficient or other device parameters may be variable, in some case in real time to render the response programmably variable.

A tunable laser for tuning a lasing mode based on light beams travelling through at least one block of channel waveguides with at least two tunable combs, includes: a frequency selective optical multiplexer comprising a first terminal for receiving/transmitting light, at least one block of channel waveguides, each channel waveguide having a reflectively coated first tail and a second tail, and an optical coupling element optically coupling the first terminal with the second tails of the channel waveguides of the at least one block of channel waveguides, each of the channel waveguides having a different length; a gain element generating a broad spectrum of light, the gain element coupling the first terminal of the frequency selective optical multiplexer with a reflective element.

A chip scale ultra violet laser source includes a plurality of laser elements on a substrate each including a back cavity mirror, a tapered gain medium, an outcoupler, a nonlinear crystal coupled to the outcoupler with a front facet that has a first coating that is anti-reflectivity (AR) to a fundamental wavelength of the laser element and high reflectivity (HR) to ultra violet wavelengths, and has an exit facet that has a second coating that has HR to a fundamental wavelength of the laser element and AR to the ultra violet wavelengths, a photodetector coupled to the outcoupler, a phase modulator coupled to the photodetector and coupled to the back cavity mirror, and a master laser diode on the substrate coupled to the phase modulator of each laser element. Each laser element emits an ultra violet beamlet and is frequency and phase locked to the master laser diode.

A hybrid optical source comprises an optical gain chip containing an optical gain material that provides an optical signal, and an optical reflector chip including an optical reflector. It also includes a semiconductor-on-insulator (SOI) chip, which comprises a semiconductor layer having a planarized surface facing the semiconductor reflector. The semiconductor layer includes: an optical coupler to redirect the optical signal to and from the planarized surface; and an optical waveguide to convey the optical signal from the optical coupler. While assembling these chips, a height of the optical gain material is referenced against the planarized surface of the semiconductor layer, a height of the optical reflector is referenced against the planarized surface of the semiconductor layer, and the optical reflector is aligned with the optical coupler, so that the optical signal emanating from the optical gain material is reflected by the optical reflector and into the optical coupler.

A tunable laser includes a reflective silicon optical amplifier (RSOA) with a reflective end and an interface end and an array of narrow-band reflectors, which each have a different center wavelength. It also includes a silicon-photonic optical switch, having an input port and N output ports that are coupled to a different narrow-band reflector in the array of narrow-band reflectors. The tunable laser also includes an optical waveguide coupled between the interface end of the RSOA and the input of the silicon-photonic optical switch. The frequency of this tunable laser can be tuned in discrete increments by selectively coupling the input port of the silicon-photonic optical switch to one of the N output ports, thereby causing the RSOA to form a lasing cavity with a selected narrow-band reflector coupled to the selected output port. The tunable laser also includes a laser output optically coupled to the lasing cavity.

A photonic integrated circuit is presented that includes a substrate, and a first and second waveguide patterned on the substrate. The first waveguide guides an input beam of radiation. The photonic integrated circuit also includes a coupling region, wherein the first and second waveguides each pass through the coupling region. One or more modulating elements are coupled to each of the first and second waveguides. The first waveguide and the second waveguide have a first facet and a second facet, respectively, and first and second reflections are generated at the first and second facets within the first and second waveguides, respectively. The one or more modulating elements coupled to each of the first and second waveguides are designed to adjust the phase of the first and second reflections before the first and second reflections pass through the coupling region.