Abstract: The present invention is directed to an ultra-compact dual quantum cascade laser assembly that nearly doubles the strength of a traditional laser in a in a single hermetically sealed micropackage. The device may comprise two quantum cascade lasers that meet at a combiner to create a single laser with a higher strength than traditional lasers. The current invention provides a path to an ultra-compact coherent beam combing arrangement that uses both dichroic beam combining and polarization beam combining techniques.

Abstract: A semiconductor laser tuned with an acousto-optic modulator. The acousto-optic modulator may generate standing waves or traveling waves. When traveling waves are used, a second acousto-optic modulator may be used in a reverse orientation to cancel out a chirp created in the first acousto-optic modulator. The acousto-optic modulator may be used with standing-wave laser resonators or ring lasers.

Abstract: The present invention is directed to an ultra-compact dual quantum cascade laser assembly that nearly doubles the strength of a traditional laser in a in a single hermetically sealed micropackage. The device may comprise two quantum cascade lasers that meet at a combiner to create a single laser with a higher strength than traditional lasers. The current invention provides a path to an ultra-compact coherent beam combing arrangement that uses both dichroic beam combining and polarization beam combining techniques.

Abstract: The present invention is directed to an ultra-compact dual quantum cascade laser assembly that nearly doubles the strength of a traditional laser in a in a single hermetically sealed micropackage. The device may comprise two quantum cascade lasers that meet at a combiner to create a single laser with a higher strength than traditional lasers. The current invention provides a path to an ultra-compact coherent beam combing arrangement that uses both dichroic beam combining and polarization beam combining techniques.

Abstract: A semiconductor laser tuned with an acousto-optic modulator. The acousto-optic modulator may generate standing waves or traveling waves. When traveling waves are used, a second acousto-optic modulator may be used in a reverse orientation to cancel out a chirp created in the first acousto-optic modulator. The acousto-optic modulator may be used with standing-wave laser resonators or ring lasers.

Abstract: The present invention is directed to an ultra-compact dual quantum cascade laser assembly that nearly doubles the strength of a traditional laser in a in a single hermetically sealed micropackage. The device may comprise two quantum cascade lasers that meet at a combiner to create a single laser with a higher strength than traditional lasers. The current invention provides a path to an ultra-compact coherent beam combing arrangement that uses both dichroic beam combining and polarization beam combining techniques.

Abstract: The present invention is directed to an ultra-compact dual quantum cascade laser assembly that nearly doubles the strength of a traditional laser in a in a single hermetically sealed micropackage. The device may comprise two quantum cascade lasers that meet at a combiner to create a single laser with a higher strength than traditional lasers. The current invention provides a path to an ultra-compact coherent beam combing arrangement that uses both dichroic beam combining and polarization beam combining techniques.

Abstract: A semiconductor laser tuned with an acousto-optic modulator. The acousto-optic modulator may generate standing waves or traveling waves. When traveling waves are used, a second acousto-optic modulator may be used in a reverse orientation to cancel out a chirp created in the first acousto-optic modulator. The acousto-optic modulator may be used with standing-wave laser resonators or ring lasers.

Abstract: A semiconductor laser tuned with an acousto-optic modulator. The acousto-optic modulator may generate standing waves or traveling waves. When traveling waves are used, a second acousto-optic modulator may be used in a reverse orientation to cancel out a chirp created in the first acousto-optic modulator. The acousto-optic modulator may be used with standing-wave laser resonators or ring lasers.

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: A system for collecting gas samples emitted from skin and detecting concentrations of specified components therein. The system includes a collection chamber housing defining an interior space, the collection chamber housing having a gas inlet, a gas outlet, and an opening. The opening is configured for enclosing a skin portion from which to receive an emitted gas sample and sealing the interior space against the skin portion. An inert gas source is connected to the gas inlet, which is capable of allowing inert gas from the inert gas source to flow into the interior space. A gas cell is connected to the gas outlet, which is capable of allowing the inert gas and the gas sample to flow from the interior space into the gas cell. As a laser travels through the gas cell, power and optoacoustic signals are measured and used to determine a concentration of the specified component.

Abstract: A system for collecting gas samples emitted from skin and detecting concentrations of specified components therein. The system includes a collection chamber housing defining an interior space, the collection chamber housing having a gas inlet, a gas outlet, and an opening. The opening is configured for enclosing a skin portion from which to receive an emitted gas sample and sealing the interior space against the skin portion. An inert gas source is connected to the gas inlet, which is capable of allowing inert gas from the inert gas source to flow into the interior space. A gas cell is connected to the gas outlet, which is capable of allowing the inert gas and the gas sample to flow from the interior space into the gas cell. As a laser travels through the gas cell, power and optoacoustic signals are measured and used to determine a concentration of the specified component.

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 method for detecting component concentrations in human gas emissions such as breath and gas emitted from skin. A gas sample containing a specified component is collected into a gas cell using a pump and a series of valves to draw the gas sample into the cell and control the gas pressure within the cell. A tunable optical radiation beam is passed through the gas cell and the amount of energy absorbed by the specified component may be measured indirectly by taking the difference between the incident and emerging beam energy or directly by optoacoustic methods. Concentrations of the specified component as small as 0.1 ppB may be determined. Additionally, the tunable optical radiation beam may be multiplexed for use with a plurality of systems utilizing the beam for medical purposes.

Abstract: A method for detecting component concentrations in human gas emissions such as breath and gas emitted from skin. A gas sample containing a specified component is collected into a gas cell using a pump and a series of valves to draw the gas sample into the cell and control the gas pressure within the cell. A tunable optical radiation beam is passed through the gas cell and the amount of energy absorbed by the specified component may be measured indirectly by taking the difference between the incident and emerging beam energy or directly by optoacoustic methods. Concentrations of the specified component as small as 0.1 ppB may be determined. Additionally, the tunable optical radiation beam may be multiplexed for use with a plurality of systems utilizing the beam for medical purposes.

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: 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 method and apparatus architecture for detecting gases, particularly hazardous gases which should be detected in miniscule amounts. High sensitivity detection of chemical warfare agents (CWAs) is set forth with very low probability of false positives (PFP) by the use of an innovative laser-photoacoustic spectrometer (L-PAS). Detection of diisopropyl methylphosphonate (DIMP), a decomposition product of Sarin and a relatively harmless surrogate for the nerve gases, is made in the presence of other gases that are expected to be interferences in an urban setting. Detection sensitivity for DIMP in the presence of these interferences of better than 0.45 ppb, which satisfies current homeland and military security requirements is shown as well as the first analysis of optical techniques for the detection of chemical warfare agents (CWAs) and toxic industrial chemicals (TICs) in real world conditions.