Broad bandwidth trace gas and standoff detection with infrared frequency comb sources

Published

March 11, 2012

Author(s)

Nathan R. Newbury, Alexander M. Zolot, Esther Baumann, Fabrizio R. Giorgetta, Florian B. Adler, Ian R. Coddington, Kevin O. Knabe, Lora L. Nugent-Glandorf, Paul A. Williams, Scott A. Diddams, Tyler W. Neely

Abstract

An optical frequency comb based on the output of a mode-locked femtosecond laser can be used in spectroscopic studies and sensing applications. The broad array of frequency modes simultaneously provides high spectral resolution and broad wavelength coverage across a large spectral band. Comb-based spectroscopic and detection approaches can additionally provide high sensitivity and rapid data acquisition without any moving parts. In this talk, we will describe several approaches for the generation and use of optical frequency combs in the near and mid-infrared (1-5 micron) for spectroscopic sensing applications. In one approach, we base the system on a femtosecond Yb:fiber laser. Through, a parametric oscillator or difference frequency generation of the Yb:fiber laser output we create a tunable mid-infrared frequency comb source (2.5-4.5 micron). Trace-gas spectroscopy is performed with detection in a two-dimensional high-resolution spectrometer after up-conversion to the 800 nm region. In a second approach, we employ an Er:fiber frequency comb and again generate a mid-infrared frequency comb through difference frequency generation. This mid-infrared comb can be used to calibrate a much higher power tunable laser spectrometer. The high frequency accuracy provided by the comb should allow for the rejection of narrow spectral lines from interferents, while the high power of the tunable CW laser should allow for high sensitivity. We have demonstrated this approach in the NIR at scan speeds of up to 1000 THz/sec and sub-MHz frequency accuracies. Finally, we have begun to use these broad bandwidth mid-infrared sources to investigate the spectroscopy of trace amounts of explosive residues deposited on surfaces. Small quantities (~10-20 micrograms) of explosive materials are deposited on metal surfaces and the spectroscopic signatures in the 3.2-3.4 micron region are acquired from scattered light.

Proceedings Title

PITTCON Conference & Expo 2012

Conference Dates

March 11-15, 2012

Conference Location

Orlando, FL

Pub Type

Conferences

Keywords

infrared and Raman, laser, molecular spectroscopy, trace analysis

Citation

Newbury, N. , Zolot, A. , Baumann, E. , Giorgetta, F. , Adler, F. , Coddington, I. , Knabe, K. , Nugent-Glandorf, L. , Williams, P. , Diddams, S. and Neely, T. (2012), Broad bandwidth trace gas and standoff detection with infrared frequency comb sources, PITTCON Conference & Expo 2012, Orlando, FL (Accessed April 29, 2024)