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Journals and Conferences
Using femtosecond time-resolved photoelectron spectroscopy we demonstrate that photoexcitation transforms monoclinic VO2 quasi-instantaneously into a metal. Thereby, we exclude an 80 fs structural bottleneck for the photoinduced electronic phase transition of VO2. First-principles many-body perturbation theory calculations reveal a high sensitivity of the… (More)
We demonstrate photothermally induced optical switching of ultra-compact hybrid Si-VO₂ ring resonators. The devices consist of a sub-micron length ~70 nm thick patch of phase-changing VO₂ integrated onto silicon ring resonators as small as 1.5 μm in radius. The semiconductor-to-metal transition (SMT) of VO₂ is triggered using a 532 nm pump laser, while… (More)
Vanadium dioxide (VO(2)) is a promising reconfigurable optical material and has long been a focus of condensed matter research owing to its distinctive semiconductor-to-metal phase transition (SMT), a feature that has stimulated recent development of thermally reconfigurable photonic, plasmonic, and metamaterial structures. Here, we integrate VO(2) onto… (More)
Optical antennas, subwavelength metallic structures resonating at visible frequencies, are a relatively new branch of antenna technology being applied in science, technology and medicine. Dynamically tuning the resonances of these antennas would increase their range of application and offer potential increases in plasmonic device efficiencies. Silver… (More)
We demonstrate dynamic reversible switching of VO2 insulator-to-metal transition (IMT) locally on the scale of 15 nm or less and control of nanoantennas, observed for the first time in the near-field. Using polarization-selective near-field imaging techniques, we simultaneously monitor the IMT in VO2 and the change of plasmons on gold infrared nanoantennas.… (More)
We directly trace the near-and midinfrared transmission change of a VO 2 thin film during an ultrafast insulator-to-metal transition triggered by high-field multiterahertz transients. Nonthermal switching into a metastable metallic state is governed solely by the amplitude of the applied terahertz field. In contrast to resonant excitation below the… (More)
We demonstrate a new, label-free, far-field super-resolution method based on an ultrafast pump-probe scheme oriented toward nanomaterial imaging. A focused pump laser excites a diffraction-limited spatial temperature profile, and the nonlinear changes in reflectance are probed. Enhanced spatial resolution is demonstrated with nanofabricated silicon and… (More)
Long regarded as a model system for studying insulator-to-metal phase transitions, the correlated electron material vanadium dioxide (VO2) is now finding novel uses in device applications. Two of its most appealing aspects are its accessible transition temperature (∼341 K) and its rich phase diagram. Strain can be used to selectively stabilize different VO2… (More)
A non-thermal insulator-metal transition in VO<sub>2</sub> has been driven by a non-resonant excitation at frequencies around 25 THz. A switching time of 80 fs is found, corresponding to approximately two cycles of the driving field.
The optical performance and morphology of VO<sub>2</sub> thins films deposited by electron beam evaporation, rf magnetron sputtering and pulsed laser deposition are compared. Laser-deposited films are strongly affected by substrate dewetting and epitaxial mismatch.