We discuss precision spectroscopy with a comb-based spectrometer at 3.4 υm. Our goal is to explore comb-based spectroscopy as an alternative method for fast, highly resolved, accurate measurements of gas line shapes. The spectrometer uses dual 1.5 υm frequency combs down converted to 3.4 υm via difference frequency generation (DFG) with a stabilized 1 υm fiber laser. One 3.4 υm comb is transmitted through methane and heterodyned against the second, offset comb to measure the gas absorption and dispersion. Doppler-broadened methane spectral lines are measured to below 1 MHz uncertainty. We also discuss the higher sensitivity alternative of a comb-assisted swept-laser DFG spectrometer.
Proceedings Title: SPIE Optical Engineering + Applications 2011
Conference Dates: August 21-26, 2011
Conference Location: San Diego, CA
Pub Type: Conferences
frequency combs, mid-IR, molecular spectroscopy