Spectral-focusing CARS spectroscopy driven by an all-PM-fiber gain-managed nonlinear amplifier

Abstract

We demonstrate a spectral-focusing coherent anti-Stokes Raman scattering (SF-CARS) spectroscopy system driven by a single all-fiber gain-managed nonlinear amplification laser. By exploiting the synergistic interplay between self-phase modulation and normal group-velocity dispersion in the gain fiber, the source directly delivers spectrally broadened pulses with an intrinsically linear chirp (pulse energy >100 nJ), eliminating external pulse stretchers and chirp-matching optics. Leveraging the intrinsic delay–frequency mapping, we achieve broadband SF-CARS detection covering a significant portion of the fingerprint region (500–1200 cm−1) with a spectral resolution of ∼13 cm−1. The system capability for sensitive and multiplex chemical analysis is validated by measurements of gaseous SF6 and liquid mixtures of benzene and DMSO. These results establish a compact, robust excitation architecture that advances SF-CARS toward turn-key coherent Raman spectroscopy and high-speed multi-component imaging.