Chirp modulation stimulated Raman scattering microscopy

Coherent Raman microscopy, a rapid, chemical-specific, label-free imaging method, can be plagued by non-Raman background signals. Existing modulation schemes mitigate these but none remove all background signals. Here we demonstrate what we believe to be a novel scheme, chirp modulation stimulated Raman scattering (CM-SRS), based upon modulating uniquely the relative sign of the quadratic phase (linear chirp) of the input lasers. CM-SRS removes all non-Raman signals and is linear in both Raman oscillator strength and concentration. We demonstrate that CM-SRS is highly sensitive, quantitative, and background-free via imaging of traditionally challenging samples and the small molecule pharmacokinetics of single living cells. (c) 2024 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement