Vanadium dioxide (VO2) is undergoing a reversible insulator-to-metal transition (MIT), subject to thermal, electrical or optical stimuli. The transition is accompanied by drastic changes in the material’s electrical and optical properties which, along the MIT broadband frequency response (from DC to microwaves, THz/ optical domains), triggered a plethora of interesting applications (DC to millimeter-waves switching, THz modulators, reconfigurable filters and antennas etc.). Here we report on optical switching of the VO2 material between its two dissimilar states when integrated in planar two terminal electrical devices and submitted to laser pulses with different temporal lengths from a high-power laser diode operating at 980 nm. During optical irradiation of VO2 films with pulses having mean powers between 15mW and 140mW at repetition rates up to 500 kHz, we monitored its resistance change, witnessing on the MIT onset. We demonstrate that the MIT in VO2 is optically triggered for pulses as short as 25 ns and energies higher than 130 nJ/pulse, with insulator-to-metal response times in the range 10-15 ns. The process is highly stable and reliable; the devices are able to perform more than one billion switching cycles at frequencies up to 400 kHz without damaging the material nor the device integrity. This optical activation scheme of VO2 emerges as a promising solution for reconfiguration applications at THz and millimeter-waves frequencies.
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