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 laser source assembly (10) for providing an assembly output beam (12) includes a first MIR laser source (352A), a second MIR laser source (352B), and a beam combiner (241). The first MIR laser source (352A) emits a first MIR beam (356A) that is in the MIR range, and the second MIR laser source (352B) emits a second MIR beam (356B) that is in the MIR range. Further, the first MIR beam (356A) has a first linear polarization and the second MIR beam (356B) has a second linear polarization. The beam combiner (241) combines the first MIR beam (356A) and the second MIR beam (356B) to provide the assembly output beam (12). More specifically, the beam combiner (241) can include a combiner element that reflects light having the second linear polarization and that transmits light having the first linear polarization.

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 optical fiber switch (16) for alternatively directing an input beam (14) to a plurality of different locations (18A) (18B) (18C) (18D) includes an input fiber (30), a redirector (32), a redirector mover (382), a first output fiber (34), and a second output fiber (36). The input fiber (30) launches the input beam (14) along an input axis (30A). The redirector (32) is positioned in the path of the input beam (14). The redirector (32) redirects the input beam (14) so that a redirected beam (42) launches from the redirector (32) along a first redirected axis (360) that is spaced apart from the input axis (30A) when the redirector (32) is positioned at a first position (346), and launches from the redirector (32) along a second redirected axis (362) that is spaced apart from the input axis (30A) when the redirector (32) is positioned at a second position (348) that is different from the first position (346).

Abstract: A laser source (10) for generating a continuously wavelength tunable light (12) includes a gain media (16), an optical output coupler (36F), a cavity collimator (38A), a diffraction grating (30), a grating beam (54), and a beam attacher (56). The diffraction grating (30) is spaced apart from the cavity collimator (38A) and the grating (30) cooperates with the optical output coupler (36F) to define an external cavity (32). The grating (30) includes a grating face surface (42A) that is in a grating plane (42B). The beam attacher (56) retains the grating beam (54) and allows the grating beam (54) and the grating (30) to effectively pivot about a pivot axis (33) that is located approximately at an intersection of a pivot plane (50) and the grating plane (42B).

Abstract: A laser source assembly (10) for providing an assembly output beam (12) includes a first MIR laser source (352A), a second MIR laser source (352B), and a beam combiner (244). The first MIR laser source (352A) emits a first MIR beam (356A) that is in the MIR range and the second MIR laser source (352B) emits a second MIR beam (356B) that is in the MIR range. Further, the beam combiner (244) spatially combines the first MIR beam (356A) and the second MIR beam (356B) to provide the assembly output beam (12). With this design, a plurality MIR laser sources (352A) (352B) can be packaged in a portable, common module, each of the MIR laser sources (352A) (352B) generates a narrow linewidth, accurately settable MIR beam (356A) (356B), and the MIR beams (356A) (356B) are combined to create a multiple watt assembly output beam (12) having the desired power. The beam combiner (244) can includes a combiner lens (364) and an output optical fiber (366).

Abstract: A laser source (10) for generating a continuously wavelength tunable light (12) includes a gain media (16), an optical output coupler (36F), a cavity collimator (38A), a diffraction grating (30), a grating beam (54), and a beam attacher (56). The gain media (16) generates the light (12), and the gain media (16) includes a first facet (36A) and a second facet (36B). The cavity collimator (38A) is spaced apart from the second facet (36B). The diffraction grating (30) is spaced apart from the cavity collimator (38A) and the grating (30) cooperates with the optical output coupler (36F) to define an external cavity (32). The grating (30) includes a grating face surface (42A) that is in a grating plane (42B). The gain media (16) has a media length (36I) and the cavity collimator (38A) has a collimator thickness (38D). The grating beam (54) retains the grating (30).

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.

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.