Femtosecond spectral phase shaping for CARS spectroscopy and imaging

Abstract

Abstract. Coherent Anti-Stokes Raman Scattering (CARS) is a third-order non-linear optical process that provides label-free, chemically selective microscopy by probing the internal vibrational structure of molecules. Due to the resonant enhancement of the CARS process, faster imaging is possible compared to Raman microscopy. CARS is unaffected by background fluorescence, but the inherent non-resonant background signal can overwhelm the resonant signal. We demonstrate how simple phase shapes on the pump (and probe) beam reduce the background signal and enhance the resonant signal. We demonstrate chemically selective microscopy using these shaped pulses on plastic beads.