Mid-infrared VIPA Spectrometer for Rapid and Broadband Trace Gas Detection

TL;DR

This paper introduces a mid-infrared VIPA spectrometer capable of rapid, broadband trace gas detection with high resolution, enabling real-time monitoring of dynamic gas concentration changes at sub-millisecond timescales.

Contribution

The work presents a novel 2-D imaging spectrometer based on VIPA disperser for fast, high-resolution molecular detection using MIR frequency combs, demonstrating unprecedented speed and spectral coverage.

Findings

Detected CH4 with >3750 resolution elements over 80 nm

Achieved <10 μs acquisition time for single images

Captured CH4 concentration changes at 375 fps

Abstract

We present and characterize 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 at 3.1 and 3.8 \mu m. We demonstrate detection of CH4 at 3.1 \mu m with >3750 resolution elements spanning >80 nm with ~600 MHz resolution in a <10 \mu s 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 per second. Changes in absorption above the noise floor of 5\times 10-4 are readily detected on the millisecond time scale, leading to important future applications such as real time monitoring of trace gas concentrations and detection of reactive intermediates.