A semiconductor laser element includes: an n-type cladding layer disposed above an n-type semiconductor substrate (a chip-like substrate); an active layer disposed above the n-type cladding layer; and a p-type cladding layer disposed above the active layer, in which the active layer includes a well layer and a barrier layer, an energy band gap of the barrier layer is larger than an energy band gap of the n-type cladding layer, and a refractive index of the barrier layer is higher than a refractive index of the n-type cladding layer.

Provided is a vertical cavity surface emitting laser diode (VCSEL). A tunnel junction with a high doping concentration is provided in the VCSEL. An n-type semiconductor layer of the tunnel junction has stress relative to the substrate, and is doped with at least one element such that the tunnel junction not only has a high doping concentration, but also the epitaxial layer can be oxidized and the oxidation rate is relatively stable during the oxidation process. Alternatively, the n-type semiconductor layer is doped with at least two elements. As a result, the oxidation process of the VCSEL can be stably performed, and the resistance of the tunnel junction with a high doping concentration is low. The tunnel junction is suitable to be arranged between two active layers of the VCSEL or between the p-type semiconductor and the n-type semiconductor layer of the VCSEL.

A quantum cascade laser includes light-emitting quantum well layers configured to emit infrared laser light by an intersubband transition; and injection quantum well layers configured to relax carrier energy. The light-emitting quantum well layers and the injection quantum well layers are stacked alternately. The injection quantum well layers relax the energy of carriers injected from the light-emitting quantum well layers, respectively. The light-emitting quantum well layers and the injection quantum well layers including barrier layers. At least one barrier layer includes first and second regions of a first ternary compound semiconductor, and a binary compound semiconductor thin film. The binary compound semiconductor thin film is provided between the first and second regions. The first ternary compound semiconductor includes Group III atoms and a Group V atom. The binary compound semiconductor thin film includes one Group III atom of the first ternary compound semiconductor and the Group V atom.

A modulation doped semiconductor laser includes a multiple quantum well composed of a plurality of layers including a plurality of first layers and a plurality of second layers stacked alternately and including an acceptor and a donor; a p-type semiconductor layer in contact with an uppermost layer of the plurality of layers; and an n-type semiconductor layer in contact with a lowermost layer of the plurality of layers, the plurality of first layers including the acceptor so that a p-type carrier concentration is 10% or more and 150% or less of the p-type semiconductor layer, the plurality of second layers containing the acceptor so that the p-type carrier concentration is 10% or more and 150% or less of the p-type semiconductor layer, the plurality of second layers containing the donor, and an effective carrier concentration corresponding to a difference between the p-type carrier concentration and an n-type carrier concentration is 10% or less of the p-type carrier concentration of the plurality of second layers.

A semiconductor optical element is configured to emit or absorb light and includes a lower structure that includes a multiple quantum well layer; an upper mesa structure that is disposed on the lower structure; a current injection structure that is disposed on the upper mesa structure, when seen from an optical axis of the emitted or absorbed light, a width of a portion of the current injection structure in contact with the upper mesa structure is smaller than a width of the upper mesa structure, the portion of the current injection structure in contact with the upper mesa structure consisting of InP, and an average refractive index of the upper mesa structure is higher than a refractive index of the InP forming the current injection structure; and an insulating film covering both side surfaces of the upper mesa structure and a part of an upper surface of the upper mesa structure.

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.

Disclosed is an optically pumped vertical cavity laser structure operating in the mid-infrared region, which has demonstrated room-temperature continuous wave operation. This structure uses a periodic gain active region with type I quantum wells comprised of InGaAsSb, and barrier/cladding regions which provide strong hole confinement and substantial pump absorption. A preferred embodiment includes at least one wafer bonded GaAs-based mirror. Several preferred embodiments also include means for wavelength tuning of mid-IR VCLs as disclosed, including a MEMS-tuning element. This document also includes systems for optical spectroscopy using the VCL as disclosed, including systems for detection concentrations of industrial and environmentally important gases.

A high-order Bragg grating single-mode laser array. The laser array is capable of performing a variety of fixed channel spacings ranging from 25 GHz to 800 GHz. The laser array from bottom to top includes an active layer interposed between a first semiconductor confinement layer with the first conductivity type doping corresponding to the substrate, and a second semiconductor confinement layer with the second conductivity type doping corresponding to an Ohmic contact layer, an insulating film on the main surface side of the semiconductor substrate except for the upper surface of the ridge, and a second electrode which is disposed on the insulating film and contacts the Ohmic contact layer located upper the semiconductor confinement layer with the second conductivity type. The semiconductor laser array includes N semiconductor laser diodes, where N is an integer greater than one.

A vertical-cavity surface-emitting laser device including a lower mirror, an upper mirror disposed over the lower mirror, an active region disposed between the lower mirror and the upper mirror, a lower n-type cladding layer disposed between the active region and the lower mirror, an upper n-type cladding layer disposed between the active region and the upper mirror, a heavily doped p-type semiconductor layer disposed between the active region and the upper n-type cladding layer, and a heavily doped n-type semiconductor layer disposed between the heavily doped p-type semiconductor layer and the upper n-type cladding layer to form a tunnel junction with the heavily doped p-type semiconductor layer.

A semiconductor laser (2) includes an n-type semiconductor substrate (1), a stack of an n-type cladding layer (4), an active layer (5), and a p-type cladding layer (6) successively stacked on the n-type semiconductor substrate (1). An optical waveguide (3) includes a non-impurity-doped core layer (9) provided on a light output side of the semiconductor laser (2) on the n-type semiconductor substrate (1) and having a larger forbidden band width than the active layer (5), and a cladding layer (10) provided on the core layer (9) and having a lower carrier concentration than the p-type cladding layer (6). The semiconductor laser (2) includes a carrier injection region (X1), and a non-carrier-injection region (X2) provided between the carrier injection region (X1) and the optical waveguide (3).