High-speed broadband Raman spectroscopy (>1000 cm^−1 bandwidth) provides label-free molecular vibrational information with fine temporal resolution, making it valuable for biomedical applications such as vibrational imaging or detecting transient molecular dynamics. Current techniques for high-speed broadband Raman spectroscopy, such as Fourier-transform coherent anti-Stokes Raman scattering (FT-CARS) spectroscopy, can probe the Raman “fingerprint” region (500-1800 cm^−1), but lack sensitivity in the low-frequency or THz region (<200 cm^−1, <6 THz), preventing measurement of rich intermolecular vibrational information. Here we demonstrate a technique combining FT-CARS spectroscopy-like optical filtering with Sagnac interferometry for simultaneous acquisition of THz and fingerprint Raman spectra at 24,000 spectra/sec.
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