Reconfigurable THz Filters Using Phase-Change Material and Integrated Heater

We report the design, fabrication, and measurements of reconfigurable terahertz (THz) filters using vanadium dioxide (VO2) phase-change material (PCM), which undergoes a transition between an insulator and metal phase at 68 °C (~341 K). The filters are made of frequency selective surfaces (FSS) and heater are integrated for VO2 excitation. Two THz spatial filters are developed. A broadband on/off filter at 0.35 THz is demonstrated with 20 dB change in transmission between the on and off states. Then, a reconfigurable stopband FSS filter with tunable rejection from 0.75 to 0.55 THz is presented. The latter shows a peak with rejection of more than 90%. The two states of both filters are achieved at relatively low temperature of 68 °C, making them suitable for practical applications. Comparisons between simulation and measurement show excellent agreement for both 0.35 THz on/off filter and 0.75 to 0.55 THz tunable filters.