Broadband coherent Raman spectroscopy based on single-pulse spectral-domain ghost imaging.

Abstract

Broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy plays a vital role in chemical sensing and label-free vibrational imaging, yet conventional methods suffer from limited acquisition speeds and complex detection schemes. Here, we demonstrate high-speed broadband CARS enabled by nonlinear spectral ghost imaging combined with time-stretch dispersive Fourier-transform (TS-DFT) spectroscopy. We exploit modulation instability to generate a stochastic supercontinuum as the Stokes source and a synchronized narrowband pulse as the pump. Reference Stokes spectra are captured at 60.5 MHz via TS-DFT, while anti-Stokes signals are detected using a single non-spectrally resolving photodetector. Correlating these signals enables broadband CARS spectral reconstruction across the fingerprint (600-1600 cm^-1) and C-H stretching (2600-3400 cm^-1) regions with 13 cm^-1 resolution and microsecond-scale acquisition times. Our method enables robust signal recovery without the need for spectral resolution in the detection path, facilitating measurements in complex biological and chemical environments.