Abstract: A system and method for standoff detection of explosives, CWAs and TICs using optical techniques. Preliminary analysis indicates detection of TNT at a distance of 0.5 km with a signal-to-noise ratio exceeding 10,000. The optical/thermal techniques apparently permit unambiguous detection of the target molecules even the presence of commonly encountered interferents. The technique, named Remote Optothermal Sensor (ROSE), has the potential for standoff detection at distances greater than one (1) kilometer.

Abstract: A system and method for standoff detection of explosives, CWAs and TICs using optical techniques. Preliminary analysis indicates detection of TNT at a distance of 0.5 km with a signal-to-noise ratio exceeding 10,000. The optical/thermal techniques apparently permit unambiguous detection of the target molecules even the presence of commonly encountered interferents. The technique, named Remote Optothermal Sensor (ROSE), has the potential for standoff detection at distances greater than one (1) kilometer.

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: An all optical fiber bit stream reader system for examining the data contents of an optical fiber involving the conversion of a temporal timing signal into a spatially located signal is provided. The invention generally comprises generating and detecting a signal indicating the presence of data, in a manner which is minimally destructive to the data. One embodiment comprises providing a piece of optical fiber that exhibits a nonlinear response through a two photon absorption process and subsequent emission of a photon corresponding to the two photon absorption process. Such a fiber could comprise a conventional doped silica fiber into which an additional dopant has been introduced. Another embodiment involves modifying the index of refraction of the cladding of the optical fiber line. This causes a fraction of the electric field or light pulse guided through the fiber (if present) to be coupled out of the fiber. Thereafter, the pulse can be detected.

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: A high efficiency, low cost, nondispersive optical multiplexing arrangement for optical beams, used a technique denominated “Reverse Laser Scanning.” In the Reverse Laser Scanning operation, different laser beams angularly meet on the rotational axis of a galvanometer-mounted mirror or the like. Upon reflection from the mirror, each of the laser beams is propagated along one defined direction by appropriate angular positioning of the galvanometer mirror. The process enables several useful deployments, including multi-chemical detection using several lasers in the same sensor, remotely operated laser switching for medical surgery and diagnosis where multiple lasers may be used, and wavelength, code, and time division multiplexing in communication systems, among others.

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.

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 tunable semiconductor laser includes gain medium, wavelength-selective element and a laser mode matching element. The wavelength-selective element comprises a first light absorbing plate operatively coupled to the laser mode matching element and provided with an array of high reflectivity mirrors as well as a second light absorbing plate with an array of narrow band pass filter mirrors operatively coupled to the high reflectivity mirror array of the first plate. The narrow band pass filter mirror array is disposed over a respective array of apertures in the second plate. The wavelength-selective element also comprises a light reflective plate with an array of retroreflectors and a third light absorbing plate with an array of apertures operatively disposed between the aperture array of the second plate and the retroreflector array.

Abstract: An all optical fiber bit stream reader system for examining the data contents of an optical fiber involving the conversion of a temporal timing signal into a spatially located signal is provided. The invention generally comprises generating and detecting a signal indicating the presence of data, in a manner which is minimally destructive to the data. One embodiment comprises providing a piece of optical fiber that exhibits a nonlinear response through a two photon absorption process and subsequent emission of a photon corresponding to the two photon absorption process. Such a fiber could comprise a conventional doped silica fiber into which an additional dopant has been introduced. Another embodiment involves modifying the index of refraction of the cladding of the optical fiber line. This causes a fraction of the electric field or light pulse guided through the fiber (if present) to be coupled out of the fiber. Thereafter, the pulse can be detected.

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 wavelength selection element for a tunable laser provides for a single laser structure system that can be made to generate any specific wavelength. The wavelength selection element comprises a transmission component which may include an arrangement of optical components mirrors designed to transmit (e.g. using an array of narrow band pass filters and/or mirrors), and a reflection component, which may include an array of stationary mirrors and MEM (Micro Electro Mechanical) mirrors that are adjustable under local or remote control, to reflect light of a specific wavelength such that the desired wavelength will be filtered from the light coming in from the laser and containing all the wavelength components and selectively reflected back through the semiconductor laser while light of other wavelengths not selected will not be reflected back through the laser.