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This paper demonstrates detection of methane using tunable diode laser spectroscopy (TDLS) through difference frequency generation (DFG) in order to address fundamental rotational-vibrational absorption lines, located around 3404 nm. Direct detection confirms that wavelength referencing of recovered lineshapes, developed for Near infra-red (Near-IR) systems, has been successfully transferred to the...
We have developed a continuous wave (CW) terahertz (THz) wave generation by near infrared laser diode (NIR-LD) pumping based on non-collinear phase-matched difference frequency generation (DFG) in a GaP crystal. The THz output power is improved at suitable length of GaP and NIR beam spot size. By using this generator, we measured spectra with high resolution.
A room-temperature broadly tunable mid-infrared laser system based on quasi-phase-matched (QPM) difference frequency generation (DFG) in a periodically poled LiNbO3(PPLN) crystal is developed. The continuous wave mid-infrared coherent radiation from 3.2 to 3.7 mum with a maximum output power of about 1 muW has been generated. Performance characteristics of the mid-infrared laser system has been carried...
We report a 4.3-mum wavelength conversion laser source using a quasi-phase-matched LiNbO3 waveguide. Using the laser source operated at ambient temperature and in the continuous wave mode, we successfully obtain CO2 isotopomer absorption lines.
An ultrabroadband frequency comb covered from 400 nm to 4.2 mum was demonstrated by shaping femtosecond Ti:sapphire laser to enhance the DFG in PPLN crystal, as our best knowledge it is the broadest comb with monolithic scheme.
There are many strong absorption lines of environmental gases in the mid-infrared region in atmospheric air, including those of greenhouse effect gases. Reported is difference frequency generation in a direct-bonded periodically poled LiNbO3 ridge waveguide in the 4.6 m band, which is the most appropriate wavelength range for observing carbon monoxide absorption spectra. It is also shown that isotopologue...
A fiber-coupled difference frequency generation laser spectrometer for measuring isotopic compositions of N2O at trace concentrations is presented. Using wavelength modulation 90/00 precision at 100 ppm is achieved. The accuracy is demonstrated with enriched samples.
Summary form only given. In this study we performed a comparison in the performance of two laser based spectroscopic techniques operating in different spectral regions for investigation of mono-(MMA, CH3NH2) and dimethyl (DMA, (CH3)2NH) amines. A near infrared (IR) system in the region of the first overtone of the N-H stretch vibration based on a cw cavity ringdown (CRD) detection technique and a...
In this paper, we demonstrate CH4 detection in ambient air by the simple wavelength scanning of a DFG output using a direct-bonded PPLN ridge WG. The spectroscopic resolution has been improved by employing pump LD oscillation mode stabilization with a fiber Bragg grating (FBG). The trace CH4 gas concentration in ambient air is 1.78 ppm, therefore, we adopt a multi-pass cell with a path length of 107...
We have developed a broadly tunable, long-wave infrared difference frequency source based on orientation-patterned GaAs. The system has been applied to both cavity ring-down spectroscopy and multi-pass absorption for high specificity, high sensitivity chemical detection.
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