Fiber-based frequency combs can provide broadband coherent light that enables new possibilities for high-accuracy, high-resolution broadband spectroscopy. We use a configuration with two coherently phase-locked combs; the output of one comb passes through the sample and is measured by heterodyne detection against the second comb. This system can be viewed as an extension of standard CW laser heterodyne spectroscopy to broadband laser heterodyne spectroscopy, or equivalently, as a coherent comb-based Fourier transform spectroscopy. It can measure both the magnitude and phase of a sample response over the spectral output of the comb. We will discuss our recent work exploring the potential of this comb-based spectroscopy including high signal-to-noise absorption/phase measurements of a molecular gas near 1550 nm as well as efforts to expand the spectral coverage more broadly over the near infrared and mid-infrared. We will also discuss an alternative configuration where the dual comb system is combined with a swept laser to provide both high accuracy and high sensitivity. Finally, we will summarize both the advantages and limitations of this technique.
Proceedings Title: American Chemical Society Fall Meeting 2010
Conference Dates: August 23-26, 2010
Conference Location: Boston, MA
Pub Type: Conferences
frequency combs, spectroscopy