A surface emitting laser according to one embodiment of the disclosure includes a stacked structure including, in order, a first DBR layer, an active layer, a second DBR layer, and a first electrically conductive contact layer. The stacked structure further includes a second electrically conductive contact layer and a two-dimensional electron gas generation layer between the first DBR layer and the active layer or in the first DBR layer. The surface emitting laser further includes a first electrode layer in contact with the first electrically conductive contact layer and a second electrode layer in contact with the second electrically conductive contact layer.

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.

A laser diode (1) includes an AlN single crystal substrate (11), an n-type cladding layer (12) formed on the substrate and including a nitride semiconductor layer having n-type conductivity, a light-emitting layer (14) formed on the n-type cladding layer and including one or more quantum wells, a p-type cladding layer (20) formed on the light-emitting layer and including a nitride semiconductor layer having p-type conductivity, and a p-type contact layer (18) formed on the p-type cladding layer and including a nitride semiconductor that includes GaN. The p-type cladding layer includes a p-type longitudinal conduction layer (16) that includes Al.sub.sGa.sub.1−sN (0.3≤s≤1), has a composition gradient such that the Al composition s decreases with increased distance from the substrate, and has a film thickness of less than 0.5 μm, and a p-type transverse conduction layer (17) that includes Al.sub.tGa.sub.1−tN (0<t≤1).

A surface-emitting laser includes a lower DBR layer, a cavity layer, and an upper DBR layer that are stacked in this order on top of a substrate, wherein the lower DBR layer has a first DBR layer, a contact layer, and a second DBR layer that are stacked in this order on top of the substrate, wherein the first DBR layer and the second DBR layer each include a plurality of first layers and a plurality of second layers that are alternately stacked, wherein the first layers and the second layers are each a semiconductor layer including aluminum, wherein a composition ratio of the aluminum of each first layer is lower than a composition ratio of the aluminum of each second layer, and wherein the second DBR layer includes 12 or more and 20 or fewer pairs of the first layers and the second layers.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

A surface-emitting semiconductor laser includes a substrate, a first electrode provided in contact with the substrate, a first light reflection layer provided over the substrate, a second light reflection layer provided over the substrate, an active layer provided between the second light reflection layer and the first light reflection layer, a current confining layer that is provided between the active layer and the second light reflection layer and includes a current injection region, a second electrode provided over the substrate, with the second light reflection layer being interposed between the second electrode and the substrate, and a contact layer that is provided between the second electrode and the second light reflection layer and includes a contact region that is in contact with the second electrode, in which the contact region has a smaller area than an area of the current injection region.

An optoelectronic semiconductor device is disclosed wherein the device is a vertical-cavity surface-emitting laser or a photodiode containing a section, the top part of which is electrically isolated from the rest of the device. The electric isolation can be realized by etching a set of holes and selective oxidation of AlGaAs layer or layers such that the oxide forms a continuous layer or layers everywhere beneath the top surface of this section. Alternatively, a device can be grown epitaxially on a semi-insulating substrate, and a round trench around a section of the device can be etched down to the semi-insulating substrate thus isolating this section electrically from the rest of the device. Then if top contact pads are deposited on top of the electrically isolated section, the pads have a low capacitance, and a pad capacitance below two hundred femto-Farads, and the total capacitance of the device below three hundred femto-Farads can be reached.

Novel ICL layering designs, ridge waveguide architectures, and processing protocols that will significantly lower the optical losses and improve the power conversion efficiencies of interband cascade lasers designed for both DFB single-mode and high-power applications. The semiconductor top cladding and metal contact layers are eliminated or significantly reduced. By instead using a dielectric or air top clad, or dielectric or air layers to supplement a thin top clad, in conjunction with lateral current injection and weak index-guiding, the present invention will substantially reduce the internal loss of such ICLs, resulting in lower lasing threshold, higher efficiency, and higher maximum power.

Building blocks are provided for on-chip chemical sensors and other highly-compact photonic integrated circuits combining interband or quantum cascade lasers and detectors with passive waveguides and other components integrated on a III-V or silicon. A MWIR or LWIR laser source is evanescently coupled into a passive extended or resonant-cavity waveguide that provides evanescent coupling to a sample gas (or liquid) for spectroscopic chemical sensing. In the case of an ICL, the uppermost layer of this passive waveguide has a relatively high index of refraction that enables it to form the core of the waveguide, while the ambient air, consisting of the sample gas, functions as the top cladding layer. A fraction of the propagating light beam is absorbed by the sample gas if it contains a chemical species having a fingerprint absorption feature within the spectral linewidth of the laser emission.

Provided are an epitaxial structure and a semiconductor chip applying same. The epitaxial structure comprises a quantum well structure, a P-type contact layer, and an electrode layer, which are stacked in sequence; the P-type contact layer comprises a first step part and a second step part that are disposed in a step shape, the second step part being closer to the quantum well structure relative to the first step part; the first step part and the second step part are filled with a first insulation part. By means of the described method, the anti-catastrophic optical mirror damage value of a semiconductor chip can be effectively improved.