Thermally tunable broadband metamaterial absorbers based on ionic liquids

In this paper, we propose an interesting thermally tunable broadband metamaterial absorber based on ionic liquids at the microwave band, which has distinct modulation characteris-tics in different frequency bands. Numerical simulation results show that the absorption decreases with the increase of temperature in the low-frequency band from 2-10GHz, which decreases to 60% at 100 degrees C. Meanwhile, the absorption increases with the increase in temperature in the high-frequency band from 25GHz to 48GHz. In addition, the absorber still has good broadband absorption without the metal substrate, and the absorption reaches more than 80% in the frequency band of 13.96-34.10GHz. As an all-dielectric metamaterial absorber, its absorption increases with the increase in temperature, which reaches more than 90% in the range of 20.44-50GHz at 100 degrees C. At last, the designed metamaterial absorbers have been fabricated based on ionic liquids, and experimental results are presented to demonstrate the validity of the proposed structure. Furthermore, the simple design and wide frequency tuning range of the absorbers can promise a great potential application in sensors, detection, and frequency-selective thermal emitters.(c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This paper proposes a thermally tunable broadband metamaterial absorber based on ionic liquids at the microwave band, which exhibits distinct modulation characteristics in different frequency bands. Numerical simulations demonstrate that the absorption decreases with temperature in the low-frequency band and increases in the high-frequency band. The absorber shows good broadband absorption even without a metal substrate. Experimental results confirm the validity of the proposed structure. The simple design and wide frequency tuning range of the absorber suggest great potential applications in sensors, detection, and frequency-selective thermal emitters.