Polarized multiplex coherent anti-Stokes Raman scattering using a picosecond laser and a fiber supercontinuum

摘要

We perform multiplex coherent anti-Stokes Raman scattering (CARS) micro-spectroscopy with a picosecondnpulsed laser and a broadband supercontinuum (SC) generated in photonic crystal fiber. CARS signalnstability is achieved using an active fiber coupler that avoids thermal and mechanical drifts. We obtain multiplexnCARS spectra for test liquids in the 600–2000 cm−1 spectral range. In addition we investigate the polarizationndependence of the CARS spectra when rotating the pump beam linear polarization state relative to the linearlynpolarized broad stokes SC. From these polarization measurements we deduce the Raman depolarization ratio,nthe resonant versus nonresonant contribution, the Raman resonance frequency, and the linewidth.