Broadband terahertz absorber based on hybrid Dirac semimetal and water

• The absorption bandwidth and intensity not only can be controlled by Fermi energy of BDS, but also can be tuned by temperature of water. • Tunable mechanism of the proposed dual-controlled absorber is to utilize the permittivity of water can be adjusted by temperature. • DS can be controlled by Fermi energy. • Field analyses are introduced to analyze and elucidate the physical origin of broadband absorption. A dual-tunable broadband metamaterial absorber based on bulk Dirac semimetal (BDS) and water is proposed in the terahertz (THz) region. Different from the traditional single controlled absorber, this proposed absorber can be adjusted by temperature and Fermi energy level. Simulation results indicate that the absorptance greater than 90% is achieved in the frequency range of 3.05 to 6.35 THz under normal incidence, when the temperature of the water and Fermi energy level of BDS are adjusted at 15 ℃ and 30 meV, respectively. Compared with the absorber without injected water or no BDS pattern, the bandwidth with absorptance over 90% has been significantly improved. Moreover, absorption bandwidth and intensity can be controlled independently or jointly by adjusting the temperature of the water or the Fermi energy of BDS instead of redesigning the devices. The mechanism of the proposed dual-controlled absorber is explained by utilizing the permittivity of water can be adjusted by different temperatures, and BDS can be controlled by employing the Fermi energy. Field analysis is introduced to investigate and elucidate the physical origin of broadband absorption. Based on the remarkable performance, our results may have potential applications in the thermal detectors and terahertz imaging areas.