VECSEL-based virtually imaged phased array spectrometer for rapid gas phase detection in the mid-infrared

We present a novel, to the best of our knowledge, system for high-resolution, time-resolved spectroscopy in the midwave infrared based on a modelocked vertical external cavity surface emitting laser (VECSEL) frequency comb coupled to a virtually imaged phased array (VIPA) spectrometer. The GHz level repetition rate of VECSEL-based systems coupled to VIPA spectrometers enables comb tooth resolved spectra without the use of additional filter cavities often required to increase comb tooth spacing. We demonstrate absorption spectroscopy on a methane (CH4) gas mixture at 2900 cm(-1) (3.4 mu m) with over 35 cm(-1) spectral bandwidth in a single image. Rapid time-resolved measurements were made using a 300 mu s exposure time with an acquisition rate limited to 125 Hz by the available camera. High-resolution absolute frequency measurements were performed by scanning the repetition rate of the VECSEL frequency comb. (C) 2020 Optical Society of America