Abstract: A sensitivity boosted laser dispersion spectroscopy system for sensing a sample in a sample cell or in an open path crossing the sample. The system includes a local oscillator arm and a sample arm containing the sample cell or the open path crossing the sample. A laser source is configured to generate a first light beam directed along the sample arm and a second light beam, the second light beam being frequency shifted and directed along the local oscillator arm. An intensity modulator/phase modulator/frequency shifter is disposed in the sample arm configured to generate a multi-frequency beam having known frequency spacing which is then passed through the sample cell to generate a sample arm output. A beam combiner is configured to combine the sample arm output and the second light beam from the local oscillator arm and generate a combined beam. A photodetector is configured to detect the combined beam for sensing the sample in the sample cell.

Abstract: A tunable diode laser absorption spectroscopy device includes a tunable diode laser. A laser driver is configured to drive the diode laser and ramp it within a particular frequency range. An analyte gas container, a reference gas container, and a fringe generating device are configured to receive the laser therethrough. An optical detector is configured to detect the laser after it has passed through the analyte gas container and/or the reference gas container, and the in-line fringe generating device. An acquisition card is configured to sample an output of the optical detector. A spectral analyzer is configured to receive output data from the acquisition card, determine a spectrum of the output data, decouple the fringe spectrum from the measured spectrum, calibrate the spectrum based on an expected ideal spectrum of both the fringe and reference gas, and determine a composition of the analyte based on the calibrated spectrum.

Abstract: A system for simultaneous optical pathlength determination and remote chemical sensing of a sample disposed along an optical path. A modulated laser source configured for modulated light emission so that at least one spectral sideband with a sideband frequency is created, the modulated light emission is directed along the optical path and sideband frequency is varied over time. A detector is configured to detect transmitted light along the optical path and generate a detected light intensity signal. A frequency down-converter is configured to receive the detected light emission signal and generate a frequency down-converted light intensity signal. A demodulator is configured to demodulate the frequency of the down-converted light intensity signal and output an instantaneous frequency. A pathlength calculator is configured to determine an optical pathlength to the sample based on the instantaneous frequency.

Abstract: An on-chip spectroscopic sensor includes a tunable diode laser. A laser driver for drives the tunable diode laser. An analyte test cavity receives a chemical sample and exposes the received chemical sample to light from the tunable diode laser. An optical detector detects light emerging from the analyte test cavity as a result of the laser exposure. A spectral analyzer determines a spectrum of the emerging light, matches and removes one or more known optical fringe patterns from the determined spectrum, and determines a composition or concentration of the chemical sample from the optical fringe pattern-removed spectrum.

Abstract: A system for simultaneous optical pathlength determination and remote chemical sensing of a sample disposed along an optical path. A modulated laser source configured for modulated light emission so that at least one spectral sideband with a sideband frequency is created, the modulated light emission is directed along the optical path and sideband frequency is varied over time. A detector is configured to detect transmitted light along the optical path and generate a detected light intensity signal. A frequency down-converter is configured to receive the detected light emission signal and generate a frequency down-converted light intensity signal. A demodulator is configured to demodulate the frequency of the down-converted light intensity signal and output an instantaneous frequency. A pathlength calculator is configured to determine an optical pathlength to the sample based on the instantaneous frequency.

Abstract: Method and apparatus for detecting a species in a dilute medium, the species having a spectral feature, the apparatus comprising: a beam source arranged to generate a first laser beam and a second laser beam coherent with each other, and having a matching chirp pattern. Beam guide arranged to pass at least the first laser beam through the dilute medium; a beam mixer arranged to mix the first and the second laser beams to form a mixed beam. Detector arranged to detect, during the chirp pattern, the mixed beam and to measure changes in the mixed beam caused by refractive index variations in the dilute medium across a spectral feature. Output providing a signal that changes in response to the measured changes.

Abstract: An apparatus and method for differential optical dispersion using a first sample and a second sample are disclosed. The apparatus includes a single frequency chirped laser source configured to generate a single frequency chirped laser beam. A first beam splitter is configured to split the single frequency chirped laser beam into first and second optical branches, the first sample being located in the first optical branch, the second sample being located in the second optical branch. A frequency shifter is located in the second optical branch, downstream of the second sample. A second beam splitter is configured to combine the first and second optical branches and generate a chirp-modulated mixed light beam. A square law detector is configured to detect the chirp-modulated mixed light beam and generate a heterodyne beatnote signal. A demodulator is configured for detection of the heterodyne beatnote signal to generate a transmission/differential optical dispersion spectrum.

Abstract: An apparatus and method for detecting refractive index variations in a sample is disclosed. The apparatus includes a multi frequency laser source configured to generate a mixed laser beam having at least two optical frequencies. A sinusoidal function generator is configured to modulate the optical frequencies to generate a chirp-modulated mixed laser beam. The chirp-modulated mixed laser beam being configured to pass through the sample. A detector is configured to detect the chirp-modulated mixed beam. A signal processer is configured to process the detected chirp-modulated mixed beam to measure refractive index variations in the sample.

Abstract: A dual-modulation Faraday rotation spectroscopic (FRS) system is disclosed. The FRS system uses an FRS sample cell configured to subject a sample to a low frequency modulated magnetic field. The system includes a polarized laser light source configured to generate a high frequency wavelength-modulated light beam incident on the sample, the high frequency wavelength-modulated light beam being modulated at a higher frequency than the low frequency modulated magnetic field. A polarizer is configured to receive from the sample a transmitted light beam having a modulated polarization having a polarization rotation and translate the modulated polarization of the transmitted light beam into an intensity modulated beam. A photodetector is configured to detect the intensity modulated beam and generate a photodetector signal. A dual demodulator is coupled to the photodetector and is configured to demodulate the photodetector signal.

Abstract: A dual-modulation Faraday rotation spectroscopic (FRS) system is disclosed. The FRS system uses an FRS sample cell configured to subject a sample to a low frequency modulated magnetic field. The system includes a polarized laser light source configured to generate a high frequency wavelength-modulated light beam incident on the sample, the high frequency wavelength-modulated light beam being modulated at a higher frequency than the low frequency modulated magnetic field. A polarizer is configured to receive from the sample a transmitted light beam having a modulated polarization having a polarization rotation and translate the modulated polarization of the transmitted light beam into an intensity modulated beam. A photodetector is configured to detect the intensity modulated beam and generate a photodetector signal. A dual demodulator is coupled to the photodetector and is configured to demodulate the photodetector signal.

Abstract: An apparatus and method for differential optical dispersion using a first sample and a second sample are disclosed. The apparatus includes a single frequency chirped laser source configured to generate a single frequency chirped laser beam. A first beam splitter is configured to split the single frequency chirped laser beam into first and second optical branches, the first sample being located in the first optical branch, the second sample being located in the second optical branch. A frequency shifter is located in the second optical branch, downstream of the second sample. A second beam splitter is configured to combine the first and second optical branches and generate a chirp-modulated mixed light beam. A square law detector is configured to detect the chirp-modulated mixed light beam and generate a heterodyne beatnote signal. A demodulator is configured for detection of the heterodyne beatnote signal to generate a transmission/differential optical dispersion spectrum.

Abstract: A novel low-power and compact laser spectroscopic sensor is described herein. Embodiments of the disclosed sensor utilize state-of-the-art microprocessors and digital processing techniques to reduce power consumption and integrate functions into a small device. In particular, novel software methods are disclosed which allow the use of low-power microprocessors which draw no more than about 0.02 W of power. Such low-power enables long battery life and allows embodiments of the sensor to be used in portable applications. In addition, the system architecture and methods described in this disclosure allow a single integrated embedded processor to control all the subsystems necessary for a laser spectroscopic sensor further reducing sensor size and power consumption. In addition, a power efficient method of calibrating a photoacoustic laser spectroscopic sensor is disclosed.

Abstract: Method and apparatus for detecting a species in a dilute medium, the species having a spectral feature, the apparatus comprising: a beam source arranged to generate a first laser beam and a second laser beam coherent with each other, and having a matching chirp pattern. Beam guide arranged to pass at least the first laser beam through the dilute medium; a beam mixer arranged to mix the first and the second laser beams to form a mixed beam. Detector arranged to detect, during the chirp pattern, the mixed beam and to measure changes in the mixed beam caused by refractive index variations in the dilute medium across a spectral feature. Output providing a signal that changes in response to the measured changes.

Abstract: An apparatus and method for detecting refractive index variations in a sample is disclosed. The apparatus includes a multi frequency laser source configured to generate a mixed laser beam having at least two optical frequencies. A sinusoidal function generator is configured to modulate the optical frequencies to generate a chirp-modulated mixed laser beam. The chirp-modulated mixed laser beam being configured to pass through the sample. A detector is configured to detect the chirp-modulated mixed beam. A signal processer is configured to process the detected chirp-modulated mixed beam to measure refractive index variations in the sample.

Abstract: A novel low-power and compact laser spectroscopic sensor is described herein. Embodiments of the disclosed sensor utilize state-of-the-art microprocessors and digital processing techniques to reduce power consumption and integrate functions into a small device. In particular, novel software methods are disclosed which allow the use of low-power microprocessors which draw no more than about 0.02 W of power. Such low-power enables long battery life and allows embodiments of the sensor to be used in portable applications. In addition, the system architecture and methods described in this disclosure allow a single integrated embedded processor to control all the subsystems necessary for a laser spectroscopic sensor further reducing sensor size and power consumption. In addition, a power efficient method of calibrating a photoacoustic laser spectroscopic sensor is disclosed.

Abstract: A novel low-power and compact laser spectroscopic sensor is described herein. Embodiments of the disclosed sensor utilize state-of-the-art microprocessors and digital processing techniques to reduce power consumption and integrate functions into a small device. In particular, novel software methods are disclosed which allow the use of low-power microprocessors which draw no more than about 0.02 W of power. Such low-power enables long battery life and allows embodiments of the sensor to be used in portable applications. In addition, the system architecture and methods described in this disclosure allow a single integrated embedded processor to control all the subsystems necessary for a laser spectroscopic sensor further reducing sensor size and power consumption. In addition, a power efficient method of calibrating a photoacoustic laser spectroscopic sensor is disclosed.

Abstract: An apparatus comprising a laser source configured to emit a light beam along a first path, an optical beam steering component configured to steer the light beam from the first path to a second path at an angle to the first path, and a diffraction grating configured to reflect back at least a portion of the light beam along the second path, wherein the angle determines an external cavity length. Included is an apparatus comprising a laser source configured to emit a light beam along a first path, a beam steering component configured to redirect the light beam to a second path at an angle to the first path, wherein the optical beam steering component is configured to change the angle at a rate of at least about one Kilohertz, and a diffraction grating configured to reflect back at least a portion of the light beam along the second path.

Abstract: A novel low-power and compact laser spectroscopic sensor is described herein. Embodiments of the disclosed sensor utilize state-of-the-art microprocessors and digital processing techniques to reduce power consumption and integrate functions into a small device. In particular, novel software methods are disclosed which allow the use of low-power microprocessors which draw no more than about 0.02 W of power. Such low-power enables long battery life and allows embodiments of the sensor to be used in portable applications. In addition, the system architecture and methods described in this disclosure allow a single integrated embedded processor to control all the subsystems necessary for a laser spectroscopic sensor further reducing sensor size and power consumption. In addition, a power efficient method of calibrating a photoacoustic laser spectroscopic sensor is disclosed.

Abstract: A widely tunable, mode-hop-free semiconductor laser operating in the mid-IR comprises a QCL laser chip having an effective QCL cavity length, a diffraction grating defining a grating angle and an external cavity length with respect to said chip, and means for controlling the QCL cavity length, the external cavity length, and the grating angle. The laser of claim 1 wherein said chip may be tuned over a range of frequencies even in the absence of an anti-reflective coating. The diffraction grating is controllably pivotable and translatable relative to said chip and the effective QCL cavity length can be adjusted by varying the injection current to the chip. The laser can be used for high resolution spectroscopic applications and multi species trace-gas detection. Mode-hopping is avoided by controlling the effective QCL cavity length, the external cavity length, and the grating angle so as to replicate a virtual pivot point.

Abstract: An apparatus comprising a laser source configured to emit a light beam along a first path, an optical beam steering component configured to steer the light beam from the first path to a second path at an angle to the first path, and a diffraction grating configured to reflect back at least a portion of the light beam along the second path, wherein the angle determines an external cavity length. Included is an apparatus comprising a laser source configured to emit a light beam along a first path, a beam steering component configured to redirect the light beam to a second path at an angle to the first path, wherein the optical beam steering component is configured to change the angle at a rate of at least about one Kilohertz, and a diffraction grating configured to reflect back at least a portion of the light beam along the second path.