Fig. 3: Phase-controlled ultrafast nanoimaging of insulator-to-metal transition in a VO2 nanobeam.
From: Ultrafast infrared nano-imaging of far-from-equilibrium carrier and vibrational dynamics
a Schematic of NIR pump (1.2 eV, ~2 mJ/cm2) infrared-probe (0.2 eV) ultrafast nanoimaging of VO2 (left) probing the complex dielectric functions of the insulator and metallic states (right, adapted from a complex refractive index measurement by Wan et al.53). b Time-domain HPP near-field interferogram acquired on a VO2 nanobeam at T = 0 ps, with the shifted phase between the ground-state INF(t) and the photoinduced state ΔIHPP(t) (inset). c The HPP signal amplitude relaxation RHPP(T) measured by the two-phase T-dependent (TD) scans at selected locations (top) and the equivalent acquired based on space-domain (SD) scans (bottom). d Ultrafast HPP nanoimaging of the VO2 nanobeam with the AFM topography. e The HPP amplitude mapping at T = 0 ps, derived from mappings at the two ELO phases, ϕ = 0 and π. f Time-dependent evolution of the HPP signal along L1 and L2 in panel e with the corresponding topography of the nanobeam.
