Fig. 3: Time-resolved FSRS measurements of the A1 modes in LiNbO3.
a, Experimental geometry. Time-resolved changes to the FSRS spectra were recorded by varying the time delay τ between the FSRS pulse pair and the mid-infrared pump pulse. b, FSRS spectra as a function of τ for a mid-infrared excitation fluence of 38 mJ cm−2 (14 MV cm−1 field strength). The two prominent features that result from mid-infrared excitation are a reduction in the amplitudes of the A1 modes (highlighted in red) and the emergence of new peaks (highlighted in blue). c, Equilibrium FSRS spectrum and pumped spectrum from b for τ = 0.05 ps. As discussed in the text, the features in the pumped spectrum can be explained under the assumption that the Raman tensors for the A1 modes change dynamically.
