Dual-function switchable terahertz metamaterial device with dynamic tuning characteristics

Abstract

A dual-function switchable terahertz (THz) device is proposed. Based on the phase transition of vanadium dioxide (VO2), dynamic switching between broadband absorption and polarization conversion is obtained. By manipulating the conductivity of photosensitive silicon through laser pumping, dynamic modulation of the amplitude in both functions is realized at the same time. Unlike the previous ones, the entire structure of the device consists of seven layers. When VO2 is in the metallic phase, our device is a broadband absorber. In frequency range of 0.78–1.81 THz, a broadband absorption with a relative bandwidth of 80% is achieved. Dynamic tuning of the absorption amplitude is achieved by changing the conductivity of the silicon, and the modulation depth is 74%. When VO2 is in the insulating phase, our device can be used as a polarization converter. In frequency range of 0.51–1.45 THz, cross-polarization conversion ratio is over 90%, and the relative bandwidth is up to 96%. Similarly, dynamic tuning of the polarization intensity is obtained, and the modulation depth is 89%. Compared with the previously reported ones, our device can achieve dynamical switching between the two functions, as well as dynamic tuning of performance at the same time, which offers a wide range of possible applications in sensors, detectors, solar cells, etc.

Keywords

• Terahertz metamaterial
• Vanadium dioxide
• Photosensitive silicon
• Absorption
• Polarization conversion