Abstract: Single-mode quantum cascade semiconductor lasers are provided. The lasers comprise a laser element, the laser element comprising a quantum cascade active layer; an upper cladding layer over the quantum cascade active layer; and a lower cladding layer under the quantum cascade active layer, wherein the quantum cascade active layer, the upper cladding layer and the lower cladding layer define a guided optical mode. The quantum cascade active layer and the upper and lower cladding layers are shaped in the form of a ridge structure having a front face, a back face opposite the front face, and a lasing face through which laser emission exits the ridge structure, the ridge structure configured such that the laser emission has a single-lobe, far-field beam pattern from the ridge structure comprising certain sections, including tapered sections, collateral sections, or both.

Abstract: Methods for the fabrication of orientation-patterned semiconductor structures are provided. The structures are light-waveguiding structures for nonlinear frequency conversion. The structures are periodically poled semiconductor heterostructures comprising a series of material domains disposed in a periodically alternating arrangement along the optical propagation axis of the waveguide. The methods of fabricating the orientation-patterned structures utilize a series of surface planarization steps at intermediate stages of the heterostucture growth process to provide interlayer interfaces having extremely low roughnesses.

Abstract: Methods for the fabrication of orientation-patterned semiconductor structures are provided. The structures are light-waveguiding structures for nonlinear frequency conversion. The structures are periodically poled semiconductor heterostructures comprising a series of material domains disposed in a periodically alternating arrangement along the optical propagation axis of the waveguide. The methods of fabricating the orientation-patterned structures utilize a series of surface planarization steps at intermediate stages of the heterostucture growth process to provide interlayer interfaces having extremely low roughnesses.

Abstract: Methods for the fabrication of orientation-patterned semiconductor structures are provided. The structures are light-waveguiding structures for nonlinear frequency conversion. The structures are periodically poled semiconductor heterostructures comprising a series of material domains disposed in a periodically alternating arrangement along the optical propagation axis of the waveguide. The methods of fabricating the orientation-patterned structures utilize a series of surface planarization steps at intermediate stages of the heterostructure growth process to provide interlayer interfaces having extremely low roughnesses.

Abstract: Semiconductor lasers comprise a substrate; an active layer configured to generate transverse magnetic (TM) polarized light under an electrical bias; an upper cladding layer; a lower cladding layer; and a distributed feedback (DFB) grating defined by the interface of a layer of metal and a layer of semiconductor under the layer of metal, the interface periodically corrugated in the longitudinal direction of the laser with a periodicity of ?DFB=m?/(2neff), wherein m>1. The DFB grating is configured such that loss of one or more antisymmetric longitudinal modes of the laser structure via absorption to the DFB grating is sufficiently maximized so as to produce lasing of a symmetric longitudinal mode of the laser with laser emission characterized by a single-lobe beam along each direction defined by the grating diffraction orders corresponding to emission away from the plane of the grating.

Abstract: Virtual substrates made by hydride vapor phase epitaxy are provided comprising a semiconductor growth substrate and a substantially strain-relaxed metamorphic buffer layer (MBL) structure comprising one or more layers of a semiconductor alloy on the growth substrate. The MBL structure is compositionally graded such that its lattice constant transitions from a lattice constant at the interface with the growth substrate that is substantially the same as the lattice constant of the growth substrate to a lattice constant at a surface opposite the interface that is different from the lattice constant of the growth substrate. The virtual substrates comprise relatively thick MBL structures (e.g., >20 ?m) and relatively thick growth substrates (e.g., >0.5 mm).

Abstract: Semiconductor lasers comprise a substrate; an active layer configured to generate transverse magnetic (TM) polarized light under an electrical bias; an upper cladding layer; a lower cladding layer; and a distributed feedback (DFB) grating defined by the interface of a layer of metal and a layer of semiconductor under the layer of metal, the interface periodically corrugated in the longitudinal direction of the laser with a periodicity of ?DFB=m?/(2neff), wherein m>1. The DFB grating is configured such that loss of one or more antisymmetric longitudinal modes of the laser structure via absorption to the DFB grating is sufficiently maximized so as to produce lasing of a symmetric longitudinal mode of the laser with laser emission characterized by a single-lobe beam along each direction defined by the grating diffraction orders corresponding to emission away from the plane of the grating.

Abstract: Virtual substrates made by hydride vapor phase epitaxy are provided comprising a semiconductor growth substrate and a substantially strain-relaxed metamorphic buffer layer (MBL) structure comprising one or more layers of a semiconductor alloy on the growth substrate. The MBL structure is compositionally graded such that its lattice constant transitions from a lattice constant at the interface with the growth substrate that is substantially the same as the lattice constant of the growth substrate to a lattice constant at a surface opposite the interface that is different from the lattice constant of the growth substrate. The virtual substrates comprise relatively thick MBL structures (e.g., >20 ?m) and relatively thick growth substrates (e.g., >0.

Abstract: Semiconductor structures, quantum cascade structures and lasers including the structures are provided. The semiconductor structures include a substrate, a metamorphic buffer layer structure over the substrate, and a quantum cascade structure including a superlattice of quantum wells and barriers over the metamorphic buffer layer structure. The substrate may be GaAs and the quantum cascade structure may be an InGaAs/InAlAs superlattice, including one or more barriers of AlAs.

Abstract: Disclosed are semiconductor microtube lasers including a semiconductor multilayer heterostructure. The multilayer heterostructure includes a substantially cylindrical optically active structure capable of light emission when under the influence of an applied electromagnetic field and a substantially cylindrical distributed feedback grating structure configured to provide optical feedback for a selected wavelength of light from the optically active region and to produce lasing action from the microtube when under the influence of an applied electromagnetic field.

Abstract: Methods for the fabrication of orientation-patterned semiconductor structures are provided. The structures are light-waveguiding structures for nonlinear frequency conversion. The structures are periodically poled semiconductor heterostructures comprising a series of material domains disposed in a periodically alternating arrangement along the optical propagation axis of the waveguide. The methods of fabricating the orientation-patterned structures utilize a series of surface planarization steps at intermediate stages of the heterostructure growth process to provide interlayer interfaces having extremely low roughnesses.

Abstract: Disclosed are semiconductor microtube lasers including a semiconductor multilayer heterostructure. The multilayer heterostructure includes a substantially cylindrical optically active structure capable of light emission when under the influence of an applied electromagnetic field and a substantially cylindrical distributed feedback grating structure configured to provide optical feedback for a selected wavelength of light from the optically active region and to produce lasing action from the microtube when under the influence of an applied electromagnetic field.

Abstract: Semiconductor structures, quantum cascade structures and lasers including the structures are provided. The semiconductor structures include a substrate, a metamorphic buffer layer structure over the substrate, and a quantum cascade structure including a superlattice of quantum wells and barriers over the metamorphic buffer layer structure. The substrate may be GaAs and the quantum cascade structure may be an InGaAs/InAlAs superlattice, including one or more barriers of AlAs.

Abstract: Semiconductor laser array devices capable of emitting mid- to long-wavelength infrared (i.e., 4-12 ?m) radiation are provided. The devices include a quantum cascade laser (QCL) structure comprising one or more active cores; an optical confinement structure; a cladding structure; and a plurality of laterally-spaced trench regions extending transversely through the optical confinement and cladding structures, and partially into the QCL structure. The trench regions, each of which comprises a lower trench layer comprising a semi-insulating material and an upper trench layer comprising a material having a refractive index that is higher than that of the semi-insulating material, define a plurality of laterally-spaced interelement regions separated by element regions in the laser array device.

Abstract: Semiconductor laser array devices capable of emitting mid- to long-wavelength infrared (i.e., 4-12 ?m) radiation are provided. The devices include a quantum cascade laser (QCL) structure comprising one or more active cores; an optical confinement structure; a cladding structure; and a plurality of laterally-spaced trench regions extending transversely through the optical confinement and cladding structures, and partially into the QCL structure. The trench regions, each of which comprises a lower trench layer comprising a semi-insulating material and an upper trench layer comprising a material having a refractive index that is higher than that of the semi-insulating material, define a plurality of laterally-spaced interelement regions separated by element regions in the laser array device.

Abstract: An intersubband quantum cascade laser structure includes multiple coupled laser stages, wherein each stage has a multilayer structure including an electron injector, an active region with at least one quantum well, and an electron reflector. Electrons injected from the injector into the active region at a high energy level relax to a lower energy level with the emission of a photon at, for example, mid-infrared wavelengths. The reflector reflects electrons at the higher energy level at which they were injected and transmits electrons from the lower energy level after emission of a photon. Multiple layers of semiconductor are formed on each side of the multistage structure to provide conduction across the device and to provide optical confinement of the photons emitted.

Abstract: A semiconductor laser and light emitting device is defined. The device comprises an electron injector and an active region adjacent to the electron injector. The active region includes at least one deep quantum well with barrier layers adjacent to either side of the quantum well or wells such that electrons injected from the electron injector into a high energy level of the quantum well relax to a lower energy level with the emission of a photon and are transmitted out to a region beyond the last barrier layer of the active region. The electron injector includes quantum well layers. The bottom of each deep quantum well or wells in the active region is lower in energy than the bottoms of the quantum well layers in the electron injector. The device may further comprise at least two stages wherein each stage contains an electron injector and an active region.

Abstract: An intersubband quantum cascade laser structure includes multiple coupled laser stages, wherein each stage has a multilayer structure including an electron injector, an active region with at least one quantum well, and an electron reflector. Electrons injected from the injector into the active region at a high energy level relax to a lower energy level with the emission of a photon at, for example, mid-infrared wavelengths. The reflector reflects electrons at the higher energy level at which they were injected and transmits electrons from the lower energy level after emission of a photon. Multiple layers of semiconductor are formed on each side of the multistage structure to provide conduction across the device and to provide optical confinement of the photons emitted.

Abstract: In accordance with the present invention, GaAs-based optoelectronic devices have an active region that includes a well layer composed of a compressively-strained semiconductor that is free, or substantially free, of nitrogen disposed between two barrier layers composed of a nitrogen- and indium-containing semiconductor.

Abstract: An intersubband quantum cascade laser structure includes multiple coupled laser stages, wherein each stage has a multilayer structure including an electron injector, an active region with at least one quantum well, and an electron reflector. Electrons injected from the injector into the active region at a high energy level relax to a lower energy level with the emission of a photon at, for example, mid-infrared wavelengths. The reflector reflects electrons at the higher energy level at which they were injected and transmits electrons from the lower energy level after emission of a photon. Multiple layers of semiconductor are formed on each side of the multistage structure to provide conduction across the device and to provide optical confinement of the photons emitted.