Abstract: A vertical-cavity surface-emitting laser (VCSEL) structure has a semiconductor bottom distributed Bragg reflector (DBR) arranged over a substrate; a metal mirror layer interposed between the bottom DBR and the substrate, wherein the metal mirror layer and bottom DBR are adapted to form a first mirror of the laser structure; and a reaction barrier layer interposed between the metal mirror layer and the bottom DBR, wherein the reaction barrier layer is adapted to reduce reaction between the metal mirror layer and the bottom DBR. A phase matching layer is interposed between the reaction barrier layer and the bottom DBR to adjust the phase of radiation reflected by the metal mirror layer such that an increased overall reflectance is obtained. The VCSEL is fabricated by bonding a first metal bonding layer formed over the bottom DBR and a metal mirror layer on a first substrate to a second metal bonding layer formed on a second substrate.

Abstract: An edge-emitting laser for generating single-longitudinal mode laser light at a lasing wavelength. A semiconductor active region amplifies, by stimulated emission, light in the laser cavity at the lasing wavelength. A first grating section adjacent to the active region and having a first reflectance and a first effective index of refraction. A second grating section adjacent to the active region and having a second reflectance and the first effective index of refraction. The first and second grating sections have a Bragg wavelength substantially equal to the lasing wavelength. A gratingless phase-shift section is disposed adjacent to the active region and between the first and second grating sections and has a second index of refraction different than the first index of refraction and a length sufficient to impart a phase shift for light at the lasing wavelength sufficient to achieve single-longitudinal mode operation.

Abstract: An embodiment of a radiation detector includes a semiconductor-based blocking structure interposed between the detector's absorption region and at least one of its contact structures. The blocking structure is adapted to prevent minority carriers generated within the adjacent contact structure from reaching the absorption region, and may also prevent minority carriers generated within the absorption region near the contact structure from entering the contact structure. Majority carriers, on the other hand, may be substantially unimpeded by the blocking structure in moving from the absorption region to the contact structure. In an embodiment, the blocking structure has a higher effective energy gap than its adjacent contact structure and than the absorption region. The interface between the blocking structure and the absorption region may be graded, so that the effective energy gap decreases gradually between the blocking structure and the absorption region.

Abstract: A surface emitting, unipolar, quantum cascade semiconductor laser is constructed of a multilayer semiconductor structure on a substrate. The laser has doped semiconductor material only of one conductivity type. The laser includes a core region having a larger effective refractive index than cladding regions. The core region includes a plurality of repeat units, each repeat unit having a nominally identical active region and a carrier injection and relaxation region. The repeat units are for quantum cascade generation of a lasing resonance mode within a lasing resonance cavity of the multilayer semiconductor structure. A diffraction grating is fabricated within the multilayer semiconductor structure. The grating resonantly couples diverging counter-propagating traveling wave beams of the laser resonance mode while also diffracting light into an upward direction perpendicular to a grating plane and toward the substrate surface, and also into a downward direction.

Abstract: The present invention is directed to a VCSEL and method of fabricating same. First, a substrate is provided. Then, a first reflector is disposed (where “disposed” includes being deposited or epitaxially grown) on the substrate, which is followed by an active region being disposed on the first reflector. Then, a second reflector is disposed on the active region such that the active region is interposed between the first reflector and the second reflector. Then, a polarizer is formed inside, or on the top or bottom of, the second reflector. The polarizer contains parallel stripes of material doped differently than that of the second reflector. The polarizer polarizes the light generated from the active region.

Abstract: An embodiment of a surface-emitting laser structure includes a first semiconductor region of a first conductivity type coupled to a first contact and a second semiconductor region of the same conductivity type coupled to a second contact. A third semiconductor region of the opposite conductivity type is coupled to a third contact and interposed between the first and second semiconductor regions. An active region is interposed between the first and third regions. In a further embodiment, the laser structure may include a variable refractive index structure interposed between the second and third semiconductor regions. In another embodiment, a surface-emitting laser structure may include an active region between a first semiconductor region of a first conductivity type coupled to a first contact, and a second semiconductor region of opposite conductivity type coupled to a second contact. A third electrical contact is dielectrically spaced from the second semiconductor region.

Abstract: A multiple reflectivity band reflector (MRBR) includes a stack of dielectric layers, arranged so that the reflector has a reflectivity profile comprising a plurality of reflectivity bands, e.g. at least first and second wavelength bands with reflectivity above a lasing threshold reflectivity, separated by a third wavelength band between the first and second wavelength bands having reflectivity below the lasing threshold reflectivity. A laser having at least a first mirror and an MRBR as the second mirror has a laser cavity, at least a portion of which is defined by the first mirror and the MRBR. An active region located within the laser cavity contains a material that is capable of stimulated emission at one or more wavelengths in the first and second wavelength bands. The gain spectrum of the laser is adjusted to select one of the first and second wavelength bands, thereby providing for lasing at a wavelength within the selected wavelength band. The laser may be, e.g.

Abstract: A metal bonded vertical-cavity surface-emitting laser (VCSEL) structure with a bottom dielectric distributed Bragg reflector (DBR) mirror, and method for fabricating the VCSEL structure. The VCSEL structure consists a metal bonding layer disposed on a submount at a bottom side of the metal bonding layer; a bottom cavity mirror comprising a bottom dielectric distributed Bragg reflector (DBR) disposed within the metal bonding layer, the bottom dielectric DBR having a reflectance band including the lasing wavelength; a bottom current-spreading layer disposed on said bottom dielectric DBR and on a substantially flat, annular top surface of said metal bonding layer; a semiconductor active region disposed on the bottom current-spreading layer, said active region capable of stimulated emission at the lasing wavelength; and a top cavity mirror disposed above the active region and having a reflectance band including the lasing wavelength.

Abstract: A multiple reflectivity band reflector (MRBR) includes a stack of dielectric layers, arranged so that the reflector has a reflectivity profile comprising a plurality of reflectivity bands, e.g. at least first and second wavelength bands with reflectivity above a lasing threshold reflectivity, separated by a third wavelength band between the first and second wavelength bands having reflectivity below the lasing threshold reflectivity. A laser having at least a first mirror and an MRBR as the second mirror has a laser cavity, at least a portion of which is defined by the first mirror and the MRBR. An active region located within the laser cavity contains a material that is capable of stimulated emission at one or more wavelengths in the first and second wavelength bands. The gain spectrum of the laser is adjusted to select one of the first and second wavelength bands, thereby providing for lasing at a wavelength within the selected wavelength band. The laser may be, e.g.

Abstract: A laser apparatus has a first mirror, a second mirror, at least a portion of which is defined by the first and second mirrors. The laser has an active region located in the laser cavity, which is capable of stimulated emission at one or more wavelengths of light. The second mirror comprises a plurality of dielectric layers arranged in parallel and having a reflectivity band with a peak reflectivity at a peak wavelength, said reflectivity band having a width of less than 1 nm at a reflectivity of 3% less than the peak reflectivity. The laser apparatus may be a tunable laser apparatus in which the peak wavelength of the reflectivity band is adjusted, thereby adjusting the lasing wavelength of the laser. The reflectivity band may be a lasing threshold reflectivity band over which the reflectivity of the second mirror is greater than a lasing threshold reflectivity which is sufficient to permit lasing.

Abstract: A monitored laser system has a laser having a first mirror; an exit mirror, at least a portion of a laser cavity defined by the first mirror and the exit mirror; and an active region located in the laser cavity, the active region containing a material that is capable of stimulated emission at one or more wavelengths of laser light within a tuning range of the laser. A multiple reflectivity band reflector (MRBR) is coupled to at least a portion of laser light emitted from the laser and transmits filtered laser light. The MRBR has a plurality of layers of material arranged in parallel such that the reflector has a plurality of reflectivity peaks within the tuning range, each reflectivity peak separated from neighboring reflectivity peak by a reflectivity trough having a trough minimum, said reflectivity peaks characterized by a peak profile and said trough minima between said reflectivity peaks characterized by a trough profile.

Abstract: A zigzag waveguide device-based apparatus and method for achieving or maintaining wavelength lock for a tunable laser designed to generate light at a selected one of a plurality of target wavelengths. The apparatus has a reflectively coupled zigzag waveguide device for receiving a portion of light output by the tunable laser, the zigzag waveguide device having a plurality of filters, each having a passband centered at a respective one of the plurality of target wavelengths, whereby said zigzag waveguide device produces a plurality of filtered light outputs. A plurality of photosensors is provided, one for each of said plurality of filters, each said filter positioned to receive a respective one of the plurality of filtered light outputs, each said filter producing a filter output signal related to the intensity of said portion of light in the passband of the corresponding filter.

Abstract: A planar lightwave circuit (PLC) module for conditioning light output from a tunable laser designed to generate light at a target wavelength. The PLC module has a substrate; a primary waveguide embedded in said substrate, said primary waveguide having an input end for receiving light from the tunable laser and an output end for outputting said light; and at least a first secondary waveguide embedded in said substrate, said first secondary waveguide receiving a first portion of said light from the tunable laser. A filter having a passband centered on the target wavelength is coupled to an output of the first secondary waveguide to receive said first portion of light, and generates a signal related to the intensity of said first portion of light in the passband centered on the target wavelength. This may be used by a processor and associated laser control circuitry for wavelength locking purposes.

Abstract: A monitored laser system includes a laser with a first mirror and an exit mirror. The laser also has a laser cavity defined at least in part by the first mirror and the exit mirror. Within the laser cavity is an active region that contains material that is capable of stimulated emission at one or more wavelengths such that laser light is emitted from the laser. A power source is coupled to the active region. A multiple reflectivity band reflector (MRBR) is coupled to at least a portion of the emitted laser light. The MRBR has at least first and second wavelength bands with reflectivity above a particular reflectivity separated by at least a third wavelength band having reflectivity below the particular reflectivity. A first photodiode is coupled to at least a portion of the filtered laser light and produces an output based on the amount and wavelength of light received.

Abstract: An adapter for coupling an air duct having an air duct mating end to a fan-driven vent unit having an air intake opening. The air duct may be a circular cross sectional air duct, for example, and the vent unit may comprise a HEPA or other filter. The adapter has a first mating section compatible with the air duct mating end (e.g., circular) for coupling the adapter to the air duct mating end, and a second mating section for coupling the adapter to the air intake opening of the fan-driven vent unit. Side walls of the adapter, between or part of the first and second mating sections, have supply-relief holes for providing a supply of air to the air intake opening when the air duct provides no air supply (e.g., when it is closed off by a damper system).

Abstract: One or more photodiode performance parameters for a photodiode are determined by first determining four data points Iph1, Voc1, Iph2, and Voc2, where Iph1 is a first short-circuit current, and Voc1 is a first open-circuit voltage, for the photodiode under a first illumination condition, and Iph2 is a second short-circuit current, and Voc2 is a second open-circuit voltage, for the photodiode under a second illumination condition. Then, at least one photodiode performance parameter for the photodiode is determined as a function of said four data points.

Abstract: A multispectral radiation detector for detecting radiation in at least two spectral bands, comprises a substrate and a layer stack grown on the substrate. The layer stack comprises at least first and second photodiodes, each photodiode having at least one strain-compensating superlattice absorbing layer substantially lattice matched to adjacent layers of the detector. Each strain-compensating superlattice absorbing layer has an energy gap responsive to radiation energy in a corresponding spectral region and different from the energy gaps of other strain-compensating superlattice absorbing layers of the detector.

Abstract: One or more photodiode performance parameters for a photodiode are determined by first determining four data points Iph1, Voc1, Iph2, and Voc2, where Iph1 is a first short-circuit current, and Voc1 is a first open-circuit voltage, for the photodiode under a first illumination condition, and Iph2 is a second short-circuit current, and Voc2 is a second open-circuit voltage, for the photodiode under a second illumination condition. Then, at least one photodiode performance parameter for the photodiode is determined as a function of said four data points.

Abstract: A vertical-cavity surface-emitting laser (VCSEL) structure has a semiconductor bottom distributed Bragg reflector (DBR) arranged over a substrate; a metal mirror layer interposed between the bottom DBR and the substrate, wherein the metal mirror layer and bottom DBR are adapted to form a first mirror of the laser structure; and a reaction barrier layer interposed between the metal mirror layer and the bottom DBR, wherein the reaction barrier layer is adapted to reduce reaction between the metal mirror layer and the bottom DBR. A phase matching layer is interposed between the reaction barrier layer and the bottom DBR to adjust the phase of radiation reflected by the metal mirror layer such that an increased overall reflectance is obtained. The VCSEL is fabricated by bonding a first metal bonding layer formed over the bottom DBR and a metal mirror layer on a first substrate to a second metal bonding layer formed on a second substrate.

Abstract: A compliant substrate for the formation of semiconductor devices includes a crystalline base layer and a thin-film crystalline layer on and loosely bonded to the base layers. The thin-film layer has a high degree of lattice flexibility. A compliant substrate for formation of semiconductor devices may also include a crystalline base layer, and, on the base layer, a thin film layer having a lattice constant different from the lattice constant of the base layer. A method for formation of a compliant substrate for formation of semiconductor devices includes forming a thin film layer on a first substrate, bonding a first surface of the thin film layer to a surface of a second substrate having a lattice constant different from the lattice constant of the thin film layer either with or without twist bonding, and removing the first substrate to expose a second surface of the thin film layer.