Abstract: An improved longwave infrared quantum cascade laser. The improvement includes a strained InxGa1-xAs/AlyIn1-yAs composition, with x and y each between 0.53 and 1, an active region emitting at a wavelength equal to or greater than 8 ?m, an energy spacing E54 equal to or greater than 50 meV, an energy spacing EC4 equal to or greater than 250 meV, and an optical waveguide with a cladding layer on each side of the active region. Each cladding layer has a doping level of about 2·1016 cm?3. The optical waveguide also has a top InP layer with a doping level of about 5·1016 cm?3 and a bottom InP layer with a doping level of about 5?1016 cm?3. Additionally, the optical waveguide has a plasmon layer with a doping level of about 8·1018 cm?3.

Abstract: An improved longwave infrared quantum cascade laser. The improvement includes a strained composition, with x and y each between 0.53 and 1, an active region emitting at a wavelength equal to or greater than 8 ?m, an energy spacing E54 equal to or greater than 50 meV, an energy spacing EC4 equal to or greater than 250 meV, and an optical waveguide with a cladding layer on each side of the active region. Each cladding layer has a doping level of about 2·1016 cm?3. The optical waveguide also has a top InP layer with a doping level of about 5·1016 cm?3 and a bottom InP layer with a doping level of about 5?1016 cm?3. Additionally, the optical waveguide has a plasmon layer with a doping level of about 8·1018 cm?3.

Abstract: An improved quantum cascade laser, the improvement comprising a longitudinally non-uniform dielectric waveguide. The waveguide includes a longitudinally straight section and a longitudinally tapered section. The length of the tapered section is between 5% and 50% of the total cavity length. The tapered section tapers at a taper angle from the facet width to the ridge width. The taper angle is smaller than the delineation angle of the waveguide.

Abstract: A quantum cascade laser having a lower laser level backfilling given by an equation that accounts for the degeneracy of energy states due to the presence of multiple subbands. For mid-infrared quantum cascade lasers at room temperature and a typical number of injector subbands, the voltage defect is between 90 meV and 110 meV at a current density of 80% of the rollover current density.

Abstract: A quantum cascade laser (QCL) having a bias-neutral design and a semiconductor with multiple layers of AlxIn1-xAs/InyGa1-yAs. The first active region barrier has a thickness of less than fourteen angstroms, and the second active region barrier has a thickness of less than eleven angstroms. The lower active region wavefunction overlaps with each of the injector level wavefunctions. Also, the laser transition is vertical at a bias close to roll-over. The injector level 3? is above a lower laser level 3, the injector level 2? is below the lower laser level 3, and the active region level 2 is confined to the active region. The lower laser level 3 is separated from the active region level 2 by the energy of the LO phonon. The remaining active region states and the remaining injector states are either above the lower laser level 3 or significantly below the active region level 2.

Abstract: A submount for a semiconductor laser. The submount has a layer of silicon carbide (SiC) and a layer of aluminum nitride (AlN) deposited on the layer of SiC. The submount is bonded to the InP-based laser by a hard solder applied to the AlN layer. Preferably, the thickness of the AlN layer is ten to twenty microns, the thickness of the SiC layer is two hundred fifty microns, and the solder is a gold-tin (AuSn) eutectic. The semiconductor laser may be a quantum cascade laser (QCL). Similar combinations of submount materials can be found for other semiconductor laser material systems and types.

Abstract: A quantum cascade laser utilizing non-resonant extraction design having a multilayered semiconductor with a single type of carrier; at least two final levels (1 and 1?) for a transition down from level 2; an energy spacing E21 greater than ELO; an energy spacing E31 of about 100 meV; and an energy spacing E32 about equal to ELO. The carrier wave function for level 1 overlaps with the carrier wave function for level 2. Likewise, the carrier wave function for level 1? overlaps with the carrier wave function for level 2. In a second version, the basic design also has an energy spacing E54 of about 90 meV, and levels 1 and 1? do not have to be spatially close to each other, provided that level 2 has significant overlap with both these levels. In a third version, there are at least three final levels (1, 1?, and 1?) for a transition down from level 2. Each of the levels 1, 1?, and 1? has a non-uniform squared wave function distribution.

Abstract: Methods and apparatus for broad tuning of single wavelength quantum cascade lasers and the use of light output from such lasers for highly sensitive detection of trace gases such as nitrogen dioxide, acetylene, and vapors of explosives such as trinitrotoluene (TNT) and triacetone triperoxide (TATP) and TATP's precursors including acetone and hydrogen peroxide. These methods and apparatus are also suitable for high sensitivity high selectivity detection of other chemical compounds including chemical warfare agents and toxic industrial chemicals. A quantum cascade laser (QCL) system that better achieves single mode, continuous, mode-hop free tuning for use in L-PAS (laser photoacoustic spectroscopy) by independently coordinating gain chip current, diffraction grating angle and external cavity length is described. An all mechanical method that achieves similar performance is also described. Additionally, methods for improving the sensor performance by critical selection of wavelengths are presented.

Abstract: Methods and apparatus for broad tuning of single wavelength quantum cascade lasers and the use of light output from such lasers for highly sensitive detection of trace gases such as nitrogen dioxide, acetylene, and vapors of explosives such as trinitrotoluene (TNT) and triacetone triperoxide (TATP) and TATP's precursors including acetone and hydrogen peroxide. These methods and apparatus are also suitable for high sensitivity, high selectivity detection of other chemical compounds including chemical warfare agents and toxic industrial chemicals. A quantum cascade laser (QCL) system that better achieves single mode, continuous, mode-hop free tuning for use in L-PAS (laser photoacoustic spectroscopy) by independently coordinating gain chip current, diffraction grating angle and external cavity length is described. An all mechanical method that achieves similar performance is also described. Additionally, methods for improving the sensor performance by critical selection of wavelengths are presented.

Abstract: Methods and apparatus for broad tuning of single wavelength quantum cascade lasers and the use of light output from such lasers for highly sensitive detection of trace gases such as nitrogen dioxide, acetylene, and vapors of explosives such as trinitrotoluene (TNT) and triacetone triperoxide (TATP) and TATP's precursors including acetone and hydrogen peroxide. These methods and apparatus are also suitable for high sensitivity, high selectivity detection of other chemical compounds including chemical warfare agents and toxic industrial chemicals. A quantum cascade laser (QCL) system that better achieves single mode, continuous, mode-hop free tuning for use in L-PAS (laser photoacoustic spectroscopy) by independently coordinating gain chip current, diffraction grating angle and external cavity length is described. An all mechanical method that achieves similar performance is also described. Additionally, methods for improving the sensor performance by critical selection of wavelengths are presented.

Abstract: Methods and apparatus for broad tuning of single wavelength quantum cascade lasers and the use of light output from such lasers for highly sensitive detection of trace gases such as nitrogen dioxide, acetylene, and vapors of explosives such as trinitrotoluene (TNT) and triacetone triperoxide (TATP) and TATP's precursors including acetone and hydrogen peroxide. These methods and apparatus are also suitable for high sensitivity, high selectivity detection of other chemical compounds including chemical warfare agents and toxic industrial chemicals. A quantum cascade laser (QCL) system that better achieves single mode, continuous, mode-hop free tuning for use in L-PAS (laser photoacoustic spectroscopy) by independently coordinating gain chip current, diffraction grating angle and external cavity length is described. An all mechanical method that achieves similar performance is also described. Additionally, methods for improving the sensor performance by critical selection of wavelengths are presented.

Abstract: Methods and apparatus for broad tuning of single wavelength quantum cascade lasers and the use of light output from such lasers for highly sensitive detection of trace gases such as nitrogen dioxide, acetylene, and vapors of explosives such as trinitrotoluene (TNT) and triacetone triperoxide (TATP) and TATP's precursors including acetone and hydrogen peroxide. These methods and apparatus are also suitable for high sensitivity, high selectivity detection of other chemical compounds including chemical warfare agents and toxic industrial chemicals. A quantum cascade laser (QCL) system that better achieves single mode, continuous, mode-hop free tuning for use in L-PAS (laser photoacoustic spectroscopy) by independently coordinating gain chip current, diffraction grating angle and external cavity length is described. An all mechanical method that achieves similar performance is also described. Additionally, methods for improving the sensor performance by critical selection of wavelengths are presented.

Abstract: Methods and apparatus for broad tuning of single wavelength quantum cascade lasers and the use of light output from such lasers for highly sensitive detection of trace gases such as nitrogen dioxide, acetylene, and vapors of explosives such as trinitrotoluene (TNT) and triacetone triperoxide (TATP) and TATP's precursors including acetone and hydrogen peroxide. These methods and apparatus are also suitable for high sensitivity, high selectivity detection of other chemical compounds including chemical warfare agents and toxic industrial chemicals. A quantum cascade laser (QCL) system that better achieves single mode, continuous, mode-hop free tuning for use in L-PAS (laser photoacoustic spectroscopy) by independently coordinating gain chip current, diffraction grating angle and external cavity length is described. An all mechanical method that achieves similar performance is also described. Additionally, methods for improving the sensor performance by critical selection of wavelengths are presented.

Abstract: A quantum cascade laser utilizing non-resonant extraction design having a multilayered semiconductor with a single type of carrier; at least two final levels (1 and 1?) for a transition down from level 2; an energy spacing E21 greater than ELO; an energy spacing E31 of about 100 meV; and an energy spacing E32 about equal to ELO. The carrier wave function for level 1 overlaps with the carrier wave function for level 2. Likewise, the carrier wave function for level 1? overlaps with the carrier wave function for level 2. In a second version, the basic design also has an energy spacing E54 of about 90 meV, and levels 1 and 1? do not have to be spatially close to each other, provided that level 2 has significant overlap with both these levels. In a third version, there are at least three final levels (1, 1?, and 1?) for a transition down from level 2. Each of the levels 1, 1?, and 1? has a non-uniform squared wave function distribution.

Abstract: Methods and apparatus for broad tuning of single wavelength quantum cascade lasers and the use of light output from such lasers for highly sensitive detection of trace gases such as nitrogen dioxide, acetylene, and vapors of explosives such as trinitrotoluene (TNT) and triacetone triperoxide (TATP) and TATP's precursors including acetone and hydrogen peroxide. These methods and apparatus are also suitable for high sensitivity, high selectivity detection of other chemical compounds including chemical warfare agents and toxic industrial chemicals. A quantum cascade laser (QCL) system that better achieves single mode, continuous, mode-hop free tuning for use in L-PAS (laser photoacoustic spectroscopy) by independently coordinating gain chip current, diffraction grating angle and external cavity length is described. An all mechanical method that achieves similar performance is also described. Additionally, methods for improving the sensor performance by critical selection of wavelengths are presented.

Abstract: Arrangements for the detection of the presence and/or concentration of an analyte in a sample of bodily fluid include diffuse transmission, diffuse reflection and edge or waveguide illumination arrangements. A vertical flow assay arrangement and/or technique is also disclosed, and includes a detection component that can be in the form of an array of optical detection elements. A number of assay pad constructions are described which may include at least one or more of the following components: a prefilter component, a reflective component, a membrane component, a reagent component, a mesh component, and a component to prevent lateral spreading.