Ultra-High Precision Sensing of Isotopic Signatures using Mid-Infrared (Dual) Frequency Comb Spectroscopy
Abstract
This project entails basic research in quantification and detection of stable isotopes of Carbon and Hydrogen that are used for source partitioning of several chemical warfare agents and explosives. The isotopic ratios are indicative of reaction kinetics, recombination mechanisms and transport in air and water in extreme environments. The sensing technique to detect and profile these isotopic species employs combination of higher-harmonic modulation spectroscopy and dual frequency comb spectroscopy. The proposed research is based on dual-comb spectroscopy, where multi-heterodyne detection is performed allowing Fourier transform spectroscopy with potentially high resolution, high sensitivity and no moving parts. Frequency comb spectroscopy in the mid-infrared region is an emerging and powerful technique that can provide large spectral bandwidth with sub-nm line resolution. The dual-comb sensing system with tuning range of 1 µm or greater will simultaneously measure (and discriminate) multiple abundant, isotopic species (carbon and hydrogen), including signatures of many hazardous chemicals in real-time. The estimated signal-to-noise ratio, SNR > 5000 leading to detection limits of pptv with sampling timescales of 1-100 µs. Quantum cascade (QC) laser-based dual-comb spectroscopy offers the possibility to acquire high-resolution spectra over a wide spectral range of several tens of cm-1 in a very short acquisition time of the order of µs. This technique combines the advantages of DFB-QC lasers, i.e. narrow linewidth and mode-hop-free tuning, with the large wavelength coverage of external cavity QC lasers. Such ultra-precise measurements are necessary for profiling low abundance isotopes and quantify uptake and emissions to constrain sources and sinks. The proposed research will enable, 1. Detection and spectral profile characterization of broadband (highly selective) chemical species in wavelengths ranges of 7 µm to 11 µm with selective bands of wavelength of fingerprints of many hazardous chemicals and explosives, namely, Sarin, Samon, several organic compounds and hydrocarbons like benzene and toluene. 2. Build capabilities at DSU, an HBCU institution with cutting-edge research in ultra-precision and high spectral resolution mid-infrared sensing with direct applications in defense and security. The research will play an important role for basic research in optics and chemical sensing relevant to initiatives by Army Research programs specifically under interdisciplinary areas of Optics and Earth Sciences of Army Research Office and Army Research Laboratory integrated with environmental and earth sciences to better understand modern day threats. The research program developed will create the next generation scientists and engineers and pipeline for defense workforce. Therefore, the project has several educational and research-based training focus areas namely, 1.) promote an effective integration of research, teaching, training and learning programs in photonic laser based systems, applied optics and optical engineering at an HBCU institution with large pool of talented underrepresented student in STEM fields, 2.) develop next-generation workforce and provide students with research training and hands-on expertise on aspects of national security, internal and external threats, and technologies required for battlefield conditions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 31, 2020
- Source ID
- W911NF2010316
Entities
People
- Mohammad Wahiduzzaman Khan
Organizations
- Army Contracting Command
- Delaware State University
- Office of the Secretary of Defense