2026-10-15T03:48:34Z https://www.scidb.cn/oai

10.57760/sciencedb.44086 2026-07-27T09:59:56Z

2026-07-27 Active-layer-selective resonant absorption lowers the modeled photothermal drive in a Si/VO₂ metasurface doi:10.57760/sciencedb.44086 en Photothermal phase-change metasurfaces are often optimized by maximizing far-field absorptance or normalized near-field amplitude, even though the thermal drive is determined by the pump power dissipated inside the phase-changing material. Here we establish a material-resolved numerical workflow for a square silicon (Si) resonator on a 150-nm VO₂ film supported by sapphire. Geometry maps identify a continuously tunable long-wavelength resonance and select a period P = 2.30 μm, a duty ratio D = 0.62, and a resonator side length L = DP = 1.43 μm. At 4.08 μm, the optimized metasurface reaches an absorptance of 0.8446, whereas the paired bare VO₂/sapphire film absorbs approximately 0.0420. A Cartesian multipole analysis identifies a magnetic-dipole-dominated current topology, with 74.6% of the retained relative magnitude assigned to the magnetic dipole, while the electric field penetrates the VO₂ layer. Direct integration of the periodic-boundary-corrected VO₂ loss gives absorptances of 0.841044 and 0.0419874 for the metasurface and bare film, respectively, corresponding to a 20.0309-fold active-layer enhancement; 80% of the metasurface VO₂ power is carried by 48.8% of the active-layer volume. A 21-state complex-index interpolation database shows that the 4.08-μm pump remains strongly absorbing along the modeled optical path, while a 3.36-μm probe provides large transmission contrast. The endpoint pump absorptances differ by only 1.95%, although the intermediate-state curve is not perfectly flat. In paired transient HEAT calculations using common solver controls and project-native thermal inputs, the effective intensity required to reach a volume-averaged phase coordinate of 0.5 at 5 ms decreases from approximately 309 to 16 W cm⁻². The corresponding 19.3-fold shift agrees with the active-layer absorption enhancement to within about 4%, providing a cross-workflow normalization check. The calculation is deliberately sequential and one-way; the fixed insulating-state source is a controlled comparative approximation, and the reported intensities are model-effective metrics rather than experimentally calibrated thresholds. vanadium dioxide; dielectric metasurface; active-layer absorption; magnetic dipole; photothermal switching; mid-infrared Zhouyuan Yan Ningning Dong Jiajing He Jun Wang RESTRICTED dataset Science Data Bank