Signal line shapes of Fourier transform cavity-enhanced frequency modulation spectroscopy with optical frequency combs
arXiv:1609.06443 · doi:10.1364/JOSAB.34.000358
Abstract
We present a thorough analysis of the signal line shapes of Fourier transform-based noise-immune cavity-enhanced optical frequency comb spectroscopy (NICE-OFCS). We discuss the signal dependence on the ratio of the modulation frequency, f, to the molecular line width, Γ. We compare a full model of the signals and a simplified absorption-like analytical model that has high accuracy for low f/Γ ratios and is much faster to compute. We verify the theory experimentally by measuring and fitting NICE-OFCS spectra of CO at 1575 nm using a system based on an Er:fiber femtosecond laser and a cavity with a finesse of ~11000.