Broadband Cavity Enhanced Dual-Comb Spectrometry for Hazardous Material Detection
Abstract
Frequency comb spectroscopy is enabling a powerful new class of sensors that can be used to simultaneously detect and quantify multiple chemical species in a gas mixture, including large molecules characteristic of chemical warfare agents. Frequency comb spectrometers operate by quantifying absorption by the molecules in the gas mixture at various wavelengths, and using this information to determine the concentration of each of the mixture components. The proposed work creates two key sensing modalities that are critical to future comb-based detection of chemical warfare agents – cavity enhanced dual-comb spectroscopy (DCS) and spatially scanned outdoor open path DCS. The dual comb technique requires only a single fast photodetector to acquire the sensor data product, and is thus capable of extremely compact implementation. When coupled with a self-contained, compact gas sample chamber, the system will offer unique attributes for chemical sensing, such as self-contained deployment and operation during low visibility conditions. By creating a laser enhancement cavity inside the sample chamber, we further improve sensitivity by increasing laser light interaction time with the sample. Overall, cavity enhanced DCS is well-matched to the intention of the chip-scale frequency comb sources under development in the DARPA SCOUT program, and presents a strong path towards a compact, handheld, broadband, ultra-high-resolution gas sensor. A portion of the proposed work also aims to support spatially scanned open path DCS. Spatial scanning of the DCS beamline enables plume mapping, source identification, and removes limitations on retroreflector placement in open path DCS. The spatial scanning will be achieved through a combination of a gimbal-mounted telescope, a UAV-mounted retroreflector, and specifically designed control algorithms for ground-to-UAV DCS. Altogether, the proposed work fully exploits novel, coherent frequency comb sources to enable high performance, fieldable, dual comb spectroscopy over both open air paths and within resonant cavities.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 20, 2016
- Source ID
- W31P4Q1510011
Entities
People
- Greg Rieker
Organizations
- Army Contracting Command
- Defense Advanced Research Projects Agency
- University of Colorado Boulder