Stabilization system for ultra-low-noise broadband mid-IR to THz dual frequency comb spectrometer for standoff chemical sensing
Abstract
As a result of the 2018 ONR DURIP award N00014-18-1-2176 Stabilized femtosecond dual-comb laser system as a pump source for the mid-IR frequency-comb standoff chemical sensor, the PI purchased a unique dual Cr-ZnS mode locked laser system (center wavelength 2.4 microm) for exploring a radically new concept of Dual Frequency Comb Spectroscopy in the strategic longwave spectral range to significantly enhance standoff molecular detection capability including detection of explosives and chemical and biological agents with high fidelity and speed. The PI team demonstrated- -The world’s broadest (3–12 microm) mid-IR frequency comb based on degenerate (subharmonic) optical parametric oscillator as a frequency downconverter. -Efficient generation of long-wave mid-IR (4-20 microm) and terahertz (1-4 THz) transients via intrapulse difference frequency generation in GaSe crystal. -Phase locking of two mode-locked Cr-ZnS lasers using 2f-to-3f interferometry and the optical lock. -Ultrasensitive detection of trace CO, N2O, NH3 molecules via dual-comb spectroscopy in the 2-12 microm range.The underlying principle for the chemical sensing is massively parallel spectroscopic probing using multi-heterodyning with a set of two mutually coherent frequency combs each consisting of some million sharp coherent spectral lines, evenly distributed over large bandwidth in the signature-rich mid-IR or THz ranges. The most important factor affecting spectrum quality, resolution, acquisition time, and sensitivity is the phase noise of the lasers (related to the mutual time jitter between the outputs of the two lasers). Minimizing the jitter requires utilization of ultra-low noise stabilization electronics for mutual locking of the two combs.The proposed Stabilization System for the dual-comb Cr-ZnS laser system consists of 1) two high-speed low-noise ULC locking electronics modules, 2) two high voltage amplifier modules (HVA) for the piezo control of the laser cavity length, and 3) two optical units to pump the Cr-ZnS amplifiers based on single-mode low-noise fiber lasers. The vendor, IMRA America, Inc., is an established world leader in fiber lasers and stabilization electronic for precision frequency combs. We will use the Stabilization System for carrier-envelope-offset stabilization, optical locking the comb to a narrow-linewidth external laser, and, ultimately, for achieving high degree of coherence between the two laser combs and locking the combs to the rubidium atomic clock for the absolute frequency referencing. Our previous generation dual comb spectroscopic system was controlled by IMRA electronics and proved to be superior to this class of spectroscopic systems.The proposed project will establish a new generation of sensors with dramatically improved capabilities for a reliable point and standoff detection of explosives and other hazardous substances in the wide range of mid-IR to THz frequencies. This instrumentation will support research-related education of students and researchers in many fields relevant to DoD- trace gas detection, standoff sensing, hyperspectral imaging with chemical identification, detection of trace molecules and their isotopologues in ambient air, and medical breath analysis.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 29, 2024
- Source ID
- FA95502310126
Entities
People
- Konstantin L. Vodopyanov
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Central Florida Board of Trustees