Our Spectrometers
Near-infrared spectrometerOur near-infrared system is based on an Er:fiber optical frequency comb, a high-finesse optical cavity and a fast-scanning Fourier transform spectrometer.
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Mid-infrared OPO based spectrometerOur first mid-infrared system is based on a doubly resonant optical parametric oscillator with an orientation-patterned GaAs crystal pumped by a femtosecond Tm:fiber laser, and two detection methods, a Fourier transform spectrometer and a continuous-filtering Vernier spectrometer. The Fourier transform spectrometer in combination with a multipass cell allows high resolution precision molecular spectroscopy over the entire tuning range of the OPO, i.e. 3-5.4 μm. The Vernier spectrometer, based on a cavity, diffraction grating and a photodiode, is faster, more compact and robust, at the expense of a lower resolution and lack of absolute frequency calibration.
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Mid-infrared DFG-based spectrometerWe have recently developed a high-power mid-infrared comb source based on difference frequency generation between the output of a femtosecond Yb:fiber laser and Raman-shifted solitons generated from the same source in a highly nonlinear fiber, using a periodically poled lithium niobate crystal. The coherent idler is tunable in the range of 2.7–4.2 μm, with average output power reaching 237 mW and pulses as short as 115 fs. We demonstrated the applicability of the source for spectroscopy by measuring absorption spectrum of acetylene at 3.0–3.1 μm.
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