Fig. 4: Nondegenerate frequency dependence and coherent contribution.
From: All-optical switching of an epsilon-near-zero plasmon resonance in indium tin oxide
We examine the pump–probe frequency dependence of Rpumped for 70 GW cm−2. a Using a TE pump, the frequency shift of the resonance is 14 THz, and independent of pump frequency. The dashed lines indicate the initial (black) and pumped (white) ENZ plasmon resonance frequency (pr: TM, 48.3°, fpr = 250…210 THz; pm: TE, 44.9°, fpm = 250…210 THz). b A TM pump highlights the two-beam coupling (TBC) for equivalent polarization and frequency. The higher pump absorption through the plasmon resonance leads to a larger, 20 THz shift of the resonance frequency (pr: TM, 48.3°, fpr = 250…210 THz; pm: TM, 44.9°, fpm = 250…210 THz). Markers indicate the time delay scans compared in c, where the probe frequency is 237 THz, while the pump frequency is either 237 THz (red, with TBC) or 217 THz (black, without TBC) (pr: TM, 48.3°, fpr = 237 THz; pm: TM, 44.9°, fpm = 237, 217 THz).
