A Bragg grating includes a lower waveguide layer, a middle waveguide layer disposed on the lower waveguide layer, an upper waveguide structure disposed on the middle waveguide layer opposite to the lower waveguide layer, and a buried layer. The upper waveguide structure includes upper waveguide elements that are arranged on a surface of the middle waveguide layer, and that are spaced apart from one another by cavities. The buried layer fills the cavity. The middle waveguide layer has a refractive index lower than that of each of the lower waveguide layer and the upper waveguide elements. The lower waveguide layer has a doping type the same as that of the middle waveguide layer. A method for manufacturing the Bragg grating is also provided.

A light emitting element includes a laminated structure 20 in which a first compound semiconductor layer 21, an active layer 23, and a second compound semiconductor layer 22 are laminated, a first light reflecting layer 41, and a second light reflecting layer 42 having a flat shape, a base surface 90 located on a side of a first surface of the first compound semiconductor layer 21 has a first region 91 (upwardly convex first-A region 91A and first-B region 91B) including a protruding portion protruding in a direction away from the active layer and a second region 92 having a flat surface, the first light reflecting layer 41 is formed at least on the first-A region 91A, a second curve formed by the first-B region 91B and a straight line formed by the second region 92 intersects at an angle exceeding 0°, and the second curve includes at least one kind of figure selected from the group consisting of a combination of a downwardly convex curve, a line segment, and an arbitrary curve.

Several VCSEL devices for long wavelength applications in wavelength range of 1200-1600 nm are described. These devices include an active region between a semiconductor DBR on a GaAs wafer and a dielectric DBR regrown on the active region. The active region includes multi-quantum layers (MQLs) confined between the active n-InP and p-InAlAs layers and a tunnel junction layer above the MQLs. The semiconductor DBR is fused to the bottom of the active region by a wafer bonding process. The design simplifies integrating the reflectors and the active region stack by having only one wafer bonding followed by regrowth of the other layers including the dielectric DBR. An air gap is fabricated either in an n-InP layer of the active region or in an air gap spacer layer on top of the semiconductor DBR. The air gap enhances optical confinement of the VCSEL. The air gap may also contain a grating.

A structure and method for providing alignment aids that are co-fabricated with the optical emission output from a laser pedestal are described. In embodiments, the alignment aids are formed using processes and masking layers that produce a ridge waveguide laser structure. The use of same masking processes for the laser and the alignment aids provides lithographic level precision in the positioning of the alignment aids in relation to the optical output from the laser device. Optoelectrical die formed with the alignment aids may be used with complementary interposer structures to enable alignment of optical output from lasers formed on the optoelectrical die with optical devices on the interposer.

A semiconductor laser element includes a ridge, and includes: a p-type first clad layer; and a p-type second clad layer arranged on the p-type first clad layer, the p-type first clad layer has a superlattice structure of an Al.sub.xGa.sub.1-xN layer and an Al.sub.yGa.sub.1-yN layer (0≤x≤y≤1), the p-type second clad layer includes Al.sub.zGa.sub.1-zN (0≤z≤y), the p-type first clad layer includes: a flat portion on which the p-type second clad layer is not arranged; and a protruding portion which protrudes upward from the flat portion and on which the p-type second clad layer is arranged, and the height of the protruding portion protruding from the flat portion is less than the thickness of the p-type first clad layer in the flat portion.

A reflecting mirror includes a first film and a second film on the first film, and has a reflection band where a center wavelength is λ. The first film includes a layer having a first average refractive index and another layer having a second average refractive index higher than the first average refractive index. The second film includes a layer having a third average refractive index and another layer having a fourth average refractive index higher than the third average refractive index. A sum of optical film thicknesses of the two layers of the first film is λ/2. A sum of optical film thicknesses of the two layers of the second film is greater than or equal to (n+1)λ/2 (n is an integer greater than or equal to 1).

An adaptive thermal management system for a gas turbine engine includes a heat exchanger transferring heat into a coolant, a temperature sensor measuring a temperature of the coolant, and a sensor assembly that measures a parameter of the coolant during operation of the gas turbine engine. The parameter measured by the sensor assembly is indicative of a capacity of the coolant to accept heat from the hot flow. A control valve governs a flow of coolant into the heat exchanger. A controller adjusts the control valve to communicate coolant to the heat exchanger based on a determined capacity of the coolant to accept heat in view of the measured temperature of the coolant and that the measured parameter of the coolant is within a predefined range.

Integrated-optics systems are presented in which an optically active device is optically coupled with a silicon waveguide via a passive compound-semiconductor waveguide. In a first region, the passive waveguide and the optically active device collectively define a composite waveguide structure, where the optically active device functions as the central ridge portion of a rib-waveguide structure. The optically active device is configured to control the vertical position of an optical mode in the composite waveguide along its length such that the optical mode is optically coupled into the passive waveguide with low loss. The passive waveguide and the silicon waveguide collectively define a vertical coupler in a second region, where the passive and silicon waveguides are configured to control the distribution of the optical mode along the length of the coupler, thereby enabling the entire mode to transition between the passive and silicon waveguides with low loss.

The invention relates to a radiation-emitting semiconductor chip, having: a semiconductor body comprising an active region which is designed to generate electromagnetic radiation; a resonator which comprises a first end region and a second end region; and at least one cut-out in the semiconductor body, said cut-out passing completely through the active region, wherein: the active region is situated in the resonator, and the cut-out defines a reflectivity for the electromagnetic radiation. The invention also relates to a radiation-emitting semiconductor component, a method for producing a radiation-emitting semiconductor chip, and a method for producing radiation-emitting semiconductor components.

A hybrid photonic integrated circuit and a method of its manufacture are provided. A SiP functional layer is fabricated on an SOI wafer. A lithium niobate thin film is bonded to the SiP functional layer. The silicon handle layer is removed from the SOI wafer to expose buried oxide, and at least one III-V die is bonded to the exposed buried oxide. In embodiments, at least one waveguiding component is fabricated in the SiP functional layer. In embodiments, the SiP functional layer comprises a top waveguiding layer.