Transient measurement of phononic states with covariance-based stochastic spectroscopy

摘要

We present a novel approach to transient Raman spectroscopy,which combines stochastic probe pulses and a covariance-based detection to measure stimulated Raman signals in alpha-quartz.A coherent broadband pump is used to simultaneously impulsively excite a range of different phonon modes,and the phase,amplitude,and energy of each mode are independently recovered as a function of the pump-probe delay by a noisy-probe and covariance-based analysis.Our experimental results and the associated theoretical description demonstrate the feasibility of 2D-Raman experiments based on the stochastic-probe schemes,with new capabilities not available in equivalent mean-value-based 2D-Raman techniques.This work unlocks the gate for nonlinear spectroscopies to capitalize on the information hidden within the noise and overlooked by a mean-value analysis.