111 results about "Mid ir lasers" patented technology

A compact mid-IR laser device utilizes a quantum cascade laser to provide mid-IR frequencies suitable for use in molecular detection by signature absorption spectra. The compact nature of the device is obtained owing to an efficient heat transfer structure, the use of a small diameter aspheric lens and a monolithic assembly structure to hold the optical elements in a fixed position relative to one another. The compact housing size may be approximately 20 cm×20 cm×20 cm or less. Efficient heat transfer is achieved using a thermoelectric cooler TEC combined with a high thermal conductivity heat spreader onto which the quantum cascade laser is thermally coupled.

A compact mid-IR laser device utilizes an external cavity to tune the laser. The external cavity may employ a Littrow or Littman cavity arrangement. In the Littrow cavity arrangement, a filter, such as a grating, is rotated to provide wavelength gain medium selectivity. In the Littman cavity arrangement, a reflector is rotated to provide tuning. A quantum cascade laser gain medium provides mid-IR frequencies suitable for use in molecular detection by signature absorption spectra. The compact nature of the device is obtained owing to an efficient heat transfer structure, the use of a small diameter aspheric lens for both the output lens and the external cavity lens and a monolithic assembly structure to hold the optical elements in a fixed position relative to one another. The compact housing size may be approximately 20 cm×20 cm×20 cm or less. Efficient heat transfer is achieved using a thermoelectric cooler TEC combined with a high thermal conductivity heat spreader onto which the quantum cascade laser gain medium is thermally coupled. The heat spreader not only serves to dissipate heat and conduct same to the TEC, but also serves as an optical platform to secure the optical elements within the housing in a fixed relationship relative on one another. The small diameter aspheric output and external cavity lens each may have a diameter of 10 mm or less and each lens is positioned to provided a collimated beam output from the quantum cascade laser gain medium. The housing is hermetically sealed to provide a rugged, light weight portable MIR laser source.

The invention discloses an iraser light source in the generation of an optical fiber type 3-5-micron continuous wave difference frequency and a method for achieving the same, wherein a pump light and a signal light adopt a wavelength sectional combining plan, a rare-earth-doped fiber laser with suitable wavelength is selected, a pump source adopts a ytterbium-doped fiber laser with a wave band of 1,060 nm and wave bands of over 1,100 nm, and the wave bands can be exchanged with each other. The signal light adopts an erbium-doped fiber laser with an S wave band, a C wave band and an L wave band, and the wave bands can be exchanged with each other. The ytterbium-doped fiber laser and the erbium-doped fiber laser emit the pump light and the signal light respectively, the pump light and the signal light are adjusted to be parallel with an optical axis of a crystal by a polarization controller respectively and are combined together by a fiber coupler, then a lens focusing system focuses the two light beams into a periodical polarization lithium niobate crystal; and by adjusting the length of the polarization cycle and the crystal temperature of the periodical polarization lithium niobate crystal, the pump light, the signal light and the difference frequency light meet a phase matching condition to finally achieve the infrared output in the generation of the difference frequency.

A method and apparatus for measuring target gas concentrations in an atmosphere. The method and apparatus emit in the atmosphere a laser beam tuned to a molecular absorption line of a target gas, receive a reflected signal affected by gas absorption of the target gas in the atmosphere, divide and direct the received signal into a first optical path and a second optical path including in one of the paths a correlation gas cell filled with a predetermined concentration of the target gas, detect transmitted signals through the first optical path and the second optical path, and calculate a target gas concentration by comparing a first signal transmitted through the first optical path to a second signal transmitted through the second optical path. The apparatus includes a laser source tunable to a specific molecular absorption line of a target gas and configured to emit in the atmosphere a laser beam having a spectral bandwidth greater than a full width of the molecular absorption line of the target gas, a receiver configured to receive a reflected signal affected by gas absorption of the target gas in the atmosphere, and at least one detector configured to detect transmitted signals through the first optical path and the second optical path.

An infrared laser in a self-optical parametric oscillation of double-cavity composite unsteady cavity mode selection pump relates to the laser field. A problem that the infrared laser in a self-optical parameter based on an Nd: MgO: PPLN crystal considers matching of high power and high beam quality base frequency light self-pump and a focusing parameter during a self-optical parameter oscillation process is solved. The laser comprises two laser diode pump sources, two energy transfer fibers, four focusing lenses, two 45 degree beam splitter mirrors, a parameter-oscillation-cavity totally-reflective mirror, a parameter oscillation cavity output mirror, the Nd: MgO: PPLN crystal, a temperature controller and an acousto-optic Q switch. Through adopting a double-cavity composite structure of a base-frequency optical resonant cavity and a parametric optical oscillation cavity, integration compactness is considered and simultaneously the two cavities completely work separately so that cavity-type structure parameter designs of the two cavities do not interfere with each other. Large base mode high beam quality base frequency optical pump can be realized, oscillation parameter light and base frequency light focusing parameters are highly matched, and energy conversion efficiency is high.

A tunable mid-infrared laser operated in a pulsed mode is coupled off-axis into a high-finesse optical cavity to produce a long-path spectrometer. The cavity receives a gas sample. Laser pulses may be wavelength-scanned by stepping an external grating, allowing the grating to mechanically settle, then measuring the ring-down with a set of laser pulses, before moving on the next wavelength. A detector receiving infrared light exiting the cavity supplies a cavity ring-down trace representative of sample absorption of the infrared pulses. A processor determines an absolute absorption spectrum of the gas sample from the ring-down trace and analyzes sample gas composition and trace concentration from that spectrum. The absorption baseline is highly reproducible and stable, improving the accuracy of multivariate fits, and the spectral resolution can be better than 0.001 cm−1 (contingent upon the laser source), allowing for high-resolution measurements of sharp absorption features.

A gas sensor system is provided, comprising: a gas cell operable so as to receive a sample gas; a vacuum system fluidically coupled to the gas cell operable to maintain the sample gas within the gas cell at a sub-ambient pressure; a pressure sensor operable to sense a pressure of the sample gas; a thermally insulated enclosure having the gas cell therein; a heat source or heat exchanger operable to influence an interior temperature of the thermally insulated enclosure; a light source within the thermally insulated enclosure operable to provide a mid-infrared (mid-IR) light into and through the gas cell; a photodetector within the thermally insulated enclosure operable to receive the attenuated mid-IR; and a control system electronically coupled to the vacuum system and to the pressure sensor operable to maintain the sample gas within the gas cell at the predetermined pressure to within one torr (1 Torr).