Coherent Raman Spectroscopy of Equilibrium Phonons with Subwavenumber Resolution

Abstract

Time-domain coherent Raman spectroscopy technique with excellent time (<120 fs) and equivalent spectral resolutions (up to ∼0.1 cm–1) has been applied to selectively measure ultrafast decay rates of optical phonons in technologically important wide-bandgap materials. The decays of intrinsic vibrations have been traced in time within multiple orders and phonon decay times varied broadly within 0.45–1.7 ps range. Primary decay routes via third- and fourth-order parametric phonon interactions have been analyzed to provide important estimates for zero-temperature decay rates and line widths for the main Raman active vibrations.