Dual-comb nonlinear Raman spectroscopy of broad molecular bands

Surface‐Enhanced Dual‐Comb Coherent Raman Spectroscopy with Nanoporous Gold Films

“…The total average time is currently limited by our refreshing time of 1/ f (= 40 ms) which could be further improved by up to three orders of magnitude with methods in ref. [19,21]. We also have to mention that limited dispersion management of our laser combs and the uneven enhancement of our NPG substrates across the comb emissions (518-545 nm) narrow down the interrogated Raman range.…”

“…Dual-comb coherent anti-Stokes Raman spectroscopy (CARS) circumvents these difficulties by providing a motionless multi-photon pump-probe scheme, [8,[18][19][20][21][22] combing high resolution reaching the intrinsic linewidth of Raman transitions, short measurement times down to a few microseconds, high contrast against spectral background due to time and frequency filtering, and simultaneous detection, with a single detector, of a broadband spectrum. This multiheterodyne technique has been refined by further developments respecting rapidness [19,21] and broad bandwidth possibly covering the entire molecular fingerprint region (400-3300 cm −1 ). [18] However, detecting molecules in a sensitive manner remains challenging for this rapid dual-comb method due to its inefficient utilization of comb modes (or teeth) for broadband Raman excitation and the nonlinear nature of coherent Raman spectroscopy (CRS).…”

Dual-comb coherent Raman spectroscopy with lasers of 1-GHz pulse repetition frequency

“…The span of the 1-GHz lasers, of 1500 cm -1 , allows in principle refresh rates δf rep up to about 10 kHz but improvements to the signal-to-noise ratio will then be required. With such future enhancements to the signal-to-noise ratio and with the recent availability of commercial Ti:Sa femtosecond oscillators of 10-GHz repetition frequency, the full potential of dual-comb coherent Raman spectroscopy without moving parts may be realized [30]. Broadband dual-comb Raman spectra measured on a microsecond-scale at a refresh rate of several tens of kHz may become within reach and dual-comb CARS might evolve into a powerful tool for studies of short-lived transient species, for high sensitivity experiments requiring rapid signal averaging, or for fast hyper-spectral imaging.…”