Antenna-assisted picosecond control of nanoscale phase-transition in vanadium dioxide

Abstract

Nanoscale devices in which the interaction with light can be configured using external control signals hold great interest for
next-generation optoelectronic circuits. Materials exhibiting a structural or electronic phase transition offer a large modulation
contrast with multi-level optical switching and memory functionalities. In addition, plasmonic nanoantennas can provide an
efficient enhancement mechanism for both the optically induced excitation and the readout of materials strategically positioned
in their local environment. Here, we demonstrate picosecond all-optical switching of the local phase transition in plasmonic
antenna-vanadium dioxide (VO2) hybrids, exploiting strong resonant field enhancement and selective optical pumping in plasmonic hotspots. Polarization- and wavelength-dependent pump–probe spectroscopy of multifrequency crossed antenna arrays
shows that nanoscale optical switching in plasmonic hotspots does not affect neighboring antennas placed within 100 nm of the
excited antennas. The antenna-assisted pumping mechanism is confirmed by numerical model calculations of the resonant,
antenna-mediated local heating on a picosecond time scale. The hybrid, nanoscale excitation mechanism results in 20 times
reduced switching energies and 5 times faster recovery times than a VO2 film without antennas, enabling fully reversible switching at over two million cycles per second and at local switching energies in the picojoule range. The hybrid solution of antennas
and VO2 provides a conceptual framework to merge the field localization and phase-transition response, enabling precise, nanoscale optical memory functionalities.

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Identifiers

ORCID for Otto L. Muskens: orcid.org/0000-0003-0693-5504

ORCID for C.H. de Groot: orcid.org/0000-0002-3850-7101

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