Disclosed is an epitaxial substrate with a 2D material interposer on a surface of a polycrystalline substrate. The ultra-thin 2D material interposer is grown by van der Waals epitaxy. The lattice constant of a surface layer of the ultra-thin 2D material interposer and the coefficient of thermal expansion of the substrate base are highly fit with those of AlGaN or GaN. The ultra-thin 2D material interposer is of a single-layer structure or a composite-layer structure. An AlGaN or GaN single crystalline epitaxial layer is grown on the ultra-thin 2D material interposer by virtue of the van der Waals epitaxy. Therefore, the large-size substrate may be manufactured with far lower costs than related single crystal wafers.

In various embodiments, controlled heating and/or cooling conditions are utilized during the fabrication of aluminum nitride single crystals and aluminum nitride bulk polycrystalline ceramics. Thermal treatments may also be utilized to control properties of aluminum nitride crystals after fabrication.

A vertical cavity light-emitting element includes a substrate, a first multilayer reflector, a semiconductor structure layer, an electrode layer, and a second multilayer reflector. The semiconductor structure layer includes a first semiconductor layer of a first conductivity type on the first multilayer reflector, a light-emitting layer on the first semiconductor layer, and a second semiconductor layer of a second conductivity type on the light-emitting layer. The electrode layer is on an upper surface of the semiconductor structure layer and is electrically in contact with the second semiconductor layer in one region of the upper surface. The second multilayer reflector covers the one region on the electrode layer and constitutes a resonator with the first multilayer reflector. The semiconductor structure layer has one recessed structure including one or a plurality of recessed portions passing through the light-emitting from the upper surface in a region surrounding the one region.

A semiconductor laser source includes a structured layer formed on a substrate made of silicon and having an upper face. The structured layer includes a passive optical component chosen from the group composed of an optical reflector and a waveguide. The component is encapsulated in silica or produced on a silica layer. At least one pad extends from a lower face of the structured layer, making direct contact with the substrate made of silicon, to an upper face flush with the upper face of the structured layer. The pad is produced entirely from silicon nitride, in order to form a thermal bridge through the structured layer. An optical amplifier is bonded directly above the passive optical component and partially to the upper face of the pad in order to dissipate the heat that it generates to the substrate made of silicon.

Embodiments include a silicon photonic chip having a substrate, an optical waveguide on a surface of the substrate and a cavity. The cavity includes an electro-optical component, configured for emitting light perpendicular to said surface and a lens element arranged on top of the electro-optical component. The lens is configured for collimating light emitted by the electro-optical component. The chip also includes a deflector arranged on top of the lens element and configured for deflecting light collimated through the latter toward the optical waveguide. The lens element includes electrical conductors connected to the electro-optical component. The electrical conductors of the lens element may for instance include one or more through vias, one or more bottom electrical lines on a bottom side of the lens element (facing the electro-optical component), and at least one top electrical line.

A surface-emitting semiconductor light-emitting device includes a first semiconductor layers, an active layer on the first semiconductor layer, a photonic crystal layer on the active layer and a second semiconductor layer on the photonic crystal layer. The photonic crystal layer include first protrusions in a first region and second protrusions in a second region. A spacing of adjacent first protrusions is greater than a spacing of adjacent second protrusions. The second semiconductor layer includes a first layer and a second layer on the first layer. The first layer covers first and second protrusions so that a first space remains between the adjacent first protrusions. The first layer includes a first portion provided between the adjacent second protrusions. The second layer includes a second portion provided between the adjacent first protrusions. The first space between the adjacent first protrusions is filled with the second portion of the second layer.

A method of fabricating a gain medium includes growing a p-type layer doped with zinc on a substrate, growing an undoped layer including one or both of InP or InGaAsP on the p-type layer, growing a region that includes multiple quantum wells (MQWs) on the undoped layer, and growing an n-type layer on the region. The undoped layer has a thickness that is sufficient to prevent Zn diffusion from the p-type layer into the region during subsequent growth or wafer fabrication steps.

Described herein are photonic integrated circuits (PICs) comprising a semiconductor optical amplifier (SOA) to output a signal comprising a plurality of wavelengths, a sensor to detect data associated with a power value of each wavelength of the output signal of the SOA, a filter to filter power values of one or more of the wavelengths of the output signal of the SOA, and control circuitry to control the filter to reduce a difference between a pre-determined power value of each filtered wavelength of the output signal of the SOA and the detected power value of each filtered wavelength of the output signal of the SOA.

A light emitting device includes: a base comprising a first wiring, a second wiring, and a third wiring; a first semiconductor laser element electrically connected to the first wiring and the second wiring, at an upper surface side of the base; a second semiconductor laser element electrically connected to the second wiring and the third wiring, at the upper surface side of the base; and a base cap fixed to the base such that the first semiconductor laser element and the second semiconductor laser element are enclosed in a space defined by the base and the base cap. The first semiconductor laser element and the second semiconductor laser element are connected in series. A portion of each of the first, second, and third wirings is exposed at the upper surface of the base at locations outside of the space defined by the base and the base cap.

A semiconductor ring laser including a closed loop laser cavity and an optical gain device that is optically interconnected with the closed loop laser cavity. The optical gain device includes a first optical gain segment and a second optical gain segment. The first optical gain segment and the second optical gain segment being non-identical, optically interconnected with each other, and electrically isolated from each other. A PIC including a semiconductor ring laser and to an opto-electronic system that includes a PIC. The opto-electronic system can be one of a transmitter, a receiver, a transceiver, a coherent transmitter, a coherent receiver and a coherent transceiver. The opto-electronic system can for example, but not exclusively, be used for telecommunication applications, LIDAR or sensor applications.