We present and analyze a 2-D imaging spectrometer based on a virtually imaged phased array (VIPA) disperser for rapid, high-resolution molecular detection using mid-infrared (MIR) frequency combs. A broad bandwidth, MIR laser source centered at ~3.1 υm incident on a CH4 sample detects >3750 resolution elements spanning >80 nm with ~600 MHz resolution in a 20 υs acquisition time. In addition to broadband detection, rapid, time-resolved single image detection is demonstrated by capturing dynamic concentration changes of CH4 at a rate of ~375 frames/s. Changes in concentration on this millisecond time scale can be differentiated between subsequent frames with superb signal-to-noise, leading to important future applications, such as real time monitoring of reaction dynamics and gas concentrations.
Citation: Optics Letters
Pub Type: Journals
Mid-Infrared, Trace Gas Detection, VIPA spectrometer