High-precision nanosecond detection of a gas absorption spectrum based on optical frequency comb time–frequency mapping

Abstract

There is an increasing demand for high-precision gas absorption spectroscopy in basic research and industrial applications, such as gas tracking and leak warning. In this Letter, a novel, to the best of our knowledge, high-precision and real-time gas detection method is proposed. A femtosecond optical frequency comb is used as the light source, and a broadening pulse containing a range of oscillation frequencies is formed after passing through a dispersive element and a Mach–Zehnder interferometer. Four absorption lines of H13C14N gas cells are measured at five different concentrations within a single pulse period. A single scan detection time of only 5 ns is obtained along with a coherence averaging accuracy of 0.0055 nm. High-precision and ultrafast detection of the gas absorption spectrum is accomplished while overcoming complexities related to the acquisition system and light source that are encountered in existing methods.

Dispersive Fourier Transform Spectrometer Based on Mode-Locked Er-Doped Fiber Laser for Ammonia Sensing

“…Another example is the implementation of self-heterodyning into the conventional DFT scheme [18], transferring the time-mapped optical spectrum to the radio-frequency Fourier space. This technique has proven useful for probing HCN absorption in the 1.5 µm range [18,19].…”