Tunable Quantum Cascade Lasers And Photoacoustic Detection Of Trace Gases, TNT, TATP and Precursors Acetone And Hydrogen Peroxide
First Claim
1. A method for obtaining power-maximized continuous tuning for a coupled cavity laser system, the steps comprising:
- a) powering a source of multiwavelength laser light at a first power level;
b) selectively reflecting said multiwavelength laser light in a cavity back to said source to select a first laser wavelength;
c) adjusting a distance of said cavity to obtain a maximum output distance for said first laser wavelength and said first power level, said maximum output distance maximizing output of the laser system at said first laser wavelength;
d) repeating steps b and c for other laser wavelengths to obtain sufficient data in to determine laser output peaks for said source at said first power level over a desired wavelength range; and
e) determining a maximizing power level for each wavelength in said wavelength range;
whereby the coupled cavity laser system operates at a maximum for a selected wavelength within said wavelength range by selecting said maximum output distance and said maximizing power level for said selected wavelength.
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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.
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Citations
12 Claims
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1. A method for obtaining power-maximized continuous tuning for a coupled cavity laser system, the steps comprising:
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a) powering a source of multiwavelength laser light at a first power level; b) selectively reflecting said multiwavelength laser light in a cavity back to said source to select a first laser wavelength; c) adjusting a distance of said cavity to obtain a maximum output distance for said first laser wavelength and said first power level, said maximum output distance maximizing output of the laser system at said first laser wavelength; d) repeating steps b and c for other laser wavelengths to obtain sufficient data in to determine laser output peaks for said source at said first power level over a desired wavelength range; and e) determining a maximizing power level for each wavelength in said wavelength range; whereby the coupled cavity laser system operates at a maximum for a selected wavelength within said wavelength range by selecting said maximum output distance and said maximizing power level for said selected wavelength. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification