Figure 3
From: Antenna-assisted picosecond control of nanoscale phase transition in vanadium dioxide
The model shows that the predominant phase-change response is caused by antenna-assisted absorption in the VO2 at plasmonic hotspots. Experimental (a) and calculated (b) switching response ΔOD/ODAnt of the antenna–VO2 hybrids for parallel (black lines) and perpendicular (red lines) polarizations for excitation and readout for (bottom to top) antenna arm lengths Lh=Lv=160, 210, 260, 310 and 360 nm (calculated antennas are 20 nm shorter). Dashed lines indicate vertical offsets. (c) Calculated heat source distribution (top panel) in antenna–VO2 hybrid with 190 nm antenna length during the pump laser pulse, calculated using the full electrodynamic model of local absorption, and the temperature increase ΔT calculated by including the time-dependent heat diffusion model for 9.2-ps pump duration. Scale bars, 100 nm. (d) Calculated energy contained in the IMT regions and conversion efficiency (% of incident energy) versus antenna length and pump polarization (arrows) for a single antenna. (e) Temperature iso-surfaces for the critical phase transition temperature, T=68 °C, for antenna lengths from 160 to 360 nm (bottom to top) and longitudinal (left row) and transverse (right row) polarizations. Scale bars, 100 nm.
