We propose numerically a terahertz Bragg reflector with two parallel bulk Dirac semimetals (BDSs) sheets separated by alternated dielectric gratings using the finite-difference time-domain (FDTD) method. The transmission of the proposed reflector can be tuned via not only varying the permittivity of the dielectric grating but also changing the period number of the unit cells. By adjusting the separation distance of the parallel BDS sheets, we can derive another degree of freedom to tune the Bragg band gap. In addition, the transmission spectra can also be freely tuned by means of alkaline metal doping. At last, the defect resonant mode is realized in the Bragg reflector. Our proposed Bragg reflector will have potential prospects in designing integrated photonic circuits at terahertz frequencies.

中文翻译：

---

在太赫兹频率下具有平行体狄拉克半金属的可调谐布拉格反射器

我们在数值上提出了一种太赫兹布拉格反射器，该反射器具有两个平行的体狄拉克半金属 (BDS) 片，使用有限差分时域 (FDTD) 方法由交替的介电光栅隔开。所提出的反射器的透射率不仅可以通过改变介电光栅的介电常数来调整，还可以通过改变单元的周期数来调整。通过调整平行 BDS 片的间隔距离，我们可以得到另一个调整布拉格带隙的自由度。此外，还可以通过碱金属掺杂的方式自由调节透射光谱。最后，在布拉格反射器中实现了缺陷谐振模式。我们提出的布拉格反射器在设计太赫兹频率的集成光子电路方面具有潜在的前景。