Asymmetric directionally selective device based on hyperbolic metamaterial slab and photonic band gap

In this paper, a theoretical research on asymmetric directional transmission-absorption device (ADTD) is proposed. Asymmetric properties based on a hyperbolic metamaterial slab (HMMS) and an angle selection function based on photonic band gaps are introduced to realize the directionally selective function. HMMS enables asymmetric properties between positive and negative incident angles. The transfer matrix method is used to calculate the transmission-absorption characteristics over a range of frequency bands in the microwave band. The ADTD consists of three basic units, unit I forms an angle selection with a right edge, unit II excites an angle selection with a left edge, and unit III creates an asymmetric transmission-absorption characteristic. The HMMS forms an absorption in the range of 16-20 GHz. The thickness of the HMMS can be adjusted to allow the asymmetric transmission-absorption bandwidth to cover a wide frequency band. HMMS implements a certain extent of angle selection, the layer-stacked metastructures enhance this effect and form a directionally selective function. Positively incident electromagnetic waves are absorbed directionally and negatively incident electromagnetic waves pass through directionally. The excellent properties of ADTD can be used to design multifunctional optical devices.