Dual-comb spectroscopy using frequency-doubled combs around 775 nm

Abstract

Two frequency-doubled combs are generated by nonlinear frequency conversion to realize spectroscopic measurements around 775 nm. Frequency-doubled interferograms are corrected in real-time by monitoring the relative instabilities between the combs at their fundamental frequency. Rubidium absorption lines are used to demonstrate the technique's accuracy and serve as absolute references to calibrate the frequency grid of computed spectra. The method allows frequency-doubled interferograms to be averaged without distortion during long periods of time. The calibrated frequency grid is validated by the measurement of the oxygen A-band. Moreover, the measurement analysis of the acetylene ν(1) + 3ν(3) overtone band has revealed some discrepancies with previous publications.

Dual-comb spectroscopy

“…DCS based on ytterbium fiber frequency combs centered at 1 μm is less common but has been used for a very early demonstration of cavity-enhanced DCS [14]. Further toward the visible spectrum, DCS based on doubled erbium fiber frequency combs at 760-780 has been used for Rb and O 2 spectroscopy [30,40], while DCS based on doubled ytterbium fiber frequency combs at 520 nm has been used for iodine spectroscopy [26].…”

“…In the approach of digital phase/timing correction, these error signals are digitized along with the interferograms. Signal processing then removes both carrier phase noise and relative timing noise by resampling the interferograms [10,17,24,30,31]. In the approach of analog adaptive sampling, these error signals are input to a set of analog electronics that corrects for any relative carrier phase noise and adjusts the digitizer sampling clock to match the difference in repetition rates [26,42,44].…”

Frequency-comb-based remote sensing of greenhouse gases over kilometer air paths

“…1d and 2, the variations in average temperature, average pressure, and dry-air volume mole fractions were, respectively: T = 293±0.5 K, P = 82250±25 Pa, [CO 2 ] VMR =397.6 ±0. 26…”

Dual-Comb Spectroscopy of Laser-Induced Plasmas

“…Previous work utilizing DCS has focused primarily on spectroscopy of systems under semi-static conditions, including atmospheric sensing of greenhouse gases 25 and high-resolution spectroscopy of gas cell-based samples [26][27][28] . Time-resolved direct comb spectroscopy with a single frequency comb has been performed using highly dispersive spectrometers to resolve individual comb teeth (e.g.…”

“…For example, with use of nonlinear optical fibers for supercontinuum generation, DCS laser systems can measure optical spectra spanning 100's of nanometers 22 . Further spectral coverage can be achieved with sum 28 and difference frequency generation 38 , and even intra-cavity high harmonic generation 39,40 to the vacuum and extreme-ultraviolet. Our approach to time-resolved DCS can also be applied to study other dynamic systems such as kinetics in chemical reactions 29 and pulsed-detonation combustion 41 .…”