Observation of Raman Optical Activity by Heterodyne-Detected Polarization-Resolved Coherent Anti-Stokes Raman Scattering

We report the first observation of Raman optical activity (ROA) by coherent anti-Stokes Raman scattering. Thanks to the more freedom of polarization configurations in coherent anti-Stokes Raman scattering than in spontaneous Raman spectroscopy, the contrast ratio of the chiral signal to the achiral background has been improved markedly. For (-)-β-pinene, it is 2 orders of magnitude better than that in the reported spontaneous ROA measurement. This is also the first measurement of ROA signal using a pulsed laser source.