식각된 VO 2 박막을 이용한 밴드-전환형 테라헤르츠파 메타물질
Band-switchable Terahertz Metamaterial Based on an Etched VO 2 Thin Film
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초록
본 논문에서는 온도 변화에 따라 절연체-금속 상전이 특성을 보이는 이산화바나듐(VO 2 )를 식각한 도선과 금속 도선을 조합한 밴드-전환형 테라헤르츠 메타물질을 제시하였다. 갭을 가지는 금속 사각 구조 가운데 식각된 VO 2 도선을 위치시킨 구조와 VO 2상전이 특성을 이용하여 제안된 메타물질의 가변성을 확보하였다. 설계한 VO 2 기반 메타물질은 VO 2 의 절연체-금속 상전이 특성에 따라 공진 주파수가 1.4 THz에서 0.7 THz으로 전환되었다. 이때, 제안한 메타물질의 절대 투과율은 0.7 THz와 1.4 THz에서 각각 78.5%와 65.8%로 높은 변화율을 가지고, 전환이 가능한 두 공진 주파수 중간 대역에서 40%와 60% 사이의 안정적인 투과 율을 보이면서 균일하게 90도의 높은 차등 위상 변위 특성을 보였다.
Abstract
We propose a band-switchable terahertz metamaterial based on an etched vanadium dioxide (VO 2 ) thin film. A line of etched VO 2 thin film was placed in the center gap of the split square-loop shape for the tunability of the metamaterial. The resonance frequency of the metamaterial can be switched from the 1.4 THz band to the 0.7 THz band, according to the insulator-metal phase transition in the VO 2 thin film. The absolute difference in the transmittance of the metamaterial was 78.5% and 65.8% at 0.7 THz and 1.4 THz respectively, according to the band switching. The differential phase shift was around 90°, and the transmittance was stably maintained between 40% and 60% in the middle band of the two switchable resonance-frequency bands.
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