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

• Published in: Light, science & applications Vol. 5; no. 10; p. e16173
• Main Authors: Muskens, Otto L, Bergamini, Luca, Wang, Yudong, Gaskell, Jeffrey M, Zabala, Nerea, de Groot, CH, Sheel, David W, Aizpurua, Javier
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2016; Springer Nature B.V; Nature Publishing Group
• Subjects: 140/125; 142/126; 639/624/399/1015; 639/766/400/1021; Antennas; Applied and Technical Physics; Atomic; Classical and Continuum Physics; Insulation; Lasers; Metals; Molecular; Nanoscience; Optical and Plasma Physics; Optical Devices; Optics; Original; original-article; Photonics; Physics; Physics and Astronomy; Plasma; nanoantenna; VO; insulator-metal phase transition; plasmonics; VO2
• ISSN: 2047-7538; 2095-5545; 2047-7538
• DOI: 10.1038/lsa.2016.173

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 (VO 2 ) 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 VO 2 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 VO 2 provides a conceptual framework to merge the field localization and phase-transition response, enabling precise, nanoscale optical memory functionalities. Optical nanoantennas: energy-efficient phase transitions Optical nanoantennas: energy-efficient phase transitions Gold nanoantennas enable phase transitions in vanadium dioxide (VO 2 ) films to be switched by 20 times less optical energy than usual. The miniaturization of optical components and the convergence of electronic and photonic technologies are creating a need for ultracompact devices that can control and switch light on length scales similar to optical wavelengths. Otto Muskens and co-workers deposited arrays of gold nanoantennas onto a VO 2 nanofilm. When these nanoantennas were illuminated by a train of near-infrared picosecond pulses, their plasmonic interaction with the light produced a highly localized hot spot in the VO 2 film, which in turn induced a phase transition for an optical pulse energy as small as 100 picojoules. In contrast, a VO 2 film without the nanoantennas required a pulse energy of 4 nanojoules or greater to induce the same phase transition.