Tunable mid-infrared patch antennas based on VO2 phase transition

The metal-insulator phase transition in vanadium oxide makes it an attractive material for developing reconfigurable infrared optoelectronic components. In this paper, we present a tunable mid-infrared plasmonic patch antenna array based on vanadium oxide. The antennas consist of a circular gold patch array separated from a metallic ground plane by a film of vanadium dioxide. As the insulator-to-metal phase transition is thermally triggered, the resonances of the antenna array redshift with reduced absorbance before they are eventually switched off. The measured tuning range is about 10% of the resonant frequency, and the modulation depth in reflection is as high as 50%. A hysteresis loop in the tuning behavior is also observed. The XRD and XPS characterizations reveal a polycrystalline and multi-phase vanadium oxide. Our demonstrated tunable patch antennas hold promise for optical switching and modulating in mid-infrared applications.