T-shaped tunable infrared optical switch based on vanadium dioxide with dual-wavelength channels

A T-shaped tunable infrared optical switch based on a plasmonic structure composed of metal nanorods and vanadium dioxide film is proposed. The dynamic adjustment strategy based on the insulator-metal transition of vanadium dioxide and polarization-sensitive properties of the switch is thoroughly investigated to achieve the modulation of the wavelength and spectral reflectance intensity. Benefiting from the phase transition of vana-dium dioxide, the optical switch can achieve two switching modes of ON and OFF states for both TE and TM polarizations of the incident light. Simulation results performed by finite-difference time-domain software show that the modulation depth of the switch can reach up to 85% at the resonance wavelength of 4270 nm under TM incident light. While the switch is illuminated with TE incident light, the modulation depth of the switch can reach 73% at the resonance wavelength of 2643 nm. In addition, when the polarizing angle of the incident light varies from 0 to 90 degrees, the intensity of the spectral reflectance of the switch monotonically decreases at the wavelength of 4270 nm. Meanwhile, the spectral reflectance monotonically increases at the wavelength of 2643 nm. Moreover, the resonance wavelength of the optical switch can be tuned by altering the length of the metal nanorods. Those dynamic adjustment approaches will provide potential applications in optical modulation and solar photovoltaic fields.