• Advanced Photonics
  • Vol. , Issue , ()
Peterson Walker, Gala de Pablo Julia, Lindley Matthew , Hiramatsu Kotaro, Goda K.
Author Affiliations
  • The University of Tokyo
  • Wuhan University
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    Abstract

    Broadband Raman spectroscopy (detection bandwidth >1,000 cm<sup>−1</sup>) is a valuable and widely-used tool for understanding samples via label-free measurements of their molecular vibrations. Two important Raman spectral regions are the chemically-specific “fingerprint” (200-1,800 cm<sup>−1</sup>) and “low-frequency” or “THz” (<200 cm<sup>−1</sup>; <6 THz) regions, which mostly contain intramolecular and intermolecular vibrations, respectively. These two regions are highly complementary; broadband simultaneous measurement of both regions can provide a big picture comprising information about molecular structures and interactions. Although techniques for acquiring broadband Raman spectra covering both regions have been demonstrated, these methods tend to have spectral acquisition rates <10 spectra/sec, prohibiting high-speed applications such as Raman imaging or vibrational detection of transient phenomena. Here, we demonstrate a single-laser method for ultrafast (24,000 spectra/sec) broadband Raman spectroscopy covering both THz and fingerprint regions. This is achieved by simultaneous detection of Sagnac-enhanced impulsive stimulated Raman scattering (SE-ISRS; THz-sensitive) and Fourier-transform coherent anti-Stokes Raman scattering (FT-CARS; fingerprint-sensitive). With dual-detection impulsive vibrational spectroscopy (DIVS), the SE-ISRS signal shows a >500× enhancement of <6.5 THz sensitivity compared to that of FT-CARS, and the FT-CARS signal shows a >10× enhancement of fingerprint sensitivity above 1,000 cm<sup>−1</sup> compared to that of SE-ISRS.
    Manuscript Accepted: Jan. 12, 2022
    Posted: Jan. 12, 2022
    DOI: AP