We propose a convertible metamaterial device with triple-band and broad-band characteristics based on bulk Dirac semimetal (BDS) and vanadium dioxide (VO₂). When VO₂ is in the fully insulating state, the proposed convertible device presents three distinctive absorption peaks in terahertz (THz) range with absorptance >98%. Absorptance spectra analysis shows a clear independence on the conductivity of VO₂ when the device act as a triple-band absorber. When VO₂ is in the fully metallic state, the convertible device expresses a broad-band absorption. In addition, this broad-band absorptivity can be continuously adjusted by changing the conductivity of VO₂. Importantly, without making any changes to the structure parameters, the system exhibits unique convertible mechanism from triple-band to broad-band absorption. Electric field distributions are further discussed to explore the physical origin of this convertible absorber. Benefitting from the variable Fermi level of BDS, resonance frequency can be dynamically tuned. This design approach combined the use of BDS and VO₂ not only paves a new way to realize a convertible absorber from triple-band to broad-band absorption, but also enables us to control the resonance frequency and absorption intensity in THz range. It is believed that the tunable converter provides plentiful applications such as modulator, energy harvesting and optic-electro switches.

我们提出了一种基于体狄拉克半金属（BDS）和二氧化钒（VO ₂）的具有三频和宽带特性的可转换超材料设备。当VO ₂处于完全绝缘状态时，所提出的可转换装置在太赫兹（THz）范围内呈现三个独特的吸收峰，吸收率> 98％。吸收光谱分析表明，当器件用作三频吸收器时，VO ₂的电导率具有明显的独立性。当VO ₂处于全金属状态时，该可转换装置表现出宽带吸收。另外，可以通过改变VO ₂的电导率来连续调节宽带吸收率。重要的是，在不改变结构参数的情况下，该系统展现了独特的可转换机制，从三频吸收到宽带吸收。进一步讨论了电场分布，以探索这种可转换吸收器的物理起源。受益于BDS的可变费米能级，可以动态调整谐振频率。这种设计方法结合了BDS和VO ₂的使用，不仅为实现从三频吸收到宽带吸收的可转换吸收器铺平了道路，而且使我们能够在THz范围内控制谐振频率和吸收强度。据信，该可调转换器提供了许多应用，例如调制器，能量收集和光电开关。