Broadband asymmetric absorption-transmission and double-band rasorber of electromagnetic waves based on superconductor ceramics metastructures-photonic crystals

Abstract

In this paper, a kind of superconductor ceramics metastructure-photonic crystals (SCMPC) is proposed to investigate the absorption and transmission properties of electromagnetic waves (EW) by combining a metastructure with multiple degrees of freedom regulation and strong energy localization characteristics of photonic crystals. Firstly, for the periodically aligned SCMPC, EW mainly realizes absorption in forward propagation and transmission in backward case. The relative bandwidth (RB) for both forward absorptivity and backward transmittance greater than 0.9 is 2.7 %, and the operating bandwidth (OB) is 696 ∼ 715 terahertz (THz), which is an asymmetric absorption-transmission (AAT) characteristics. Importantly, the periodically aligned SCMPC can realize the double-band rasorber phenomenon, and the forward EW exhibits an absorption-transmission-absorption phenomenon with OBs of 644.2 ∼ 671.1 THz, 700.9 ∼ 742.1 THz, and 766.8 ∼ 784.2 THz. RBs with absorption and transmissivity greater than 0.8 are 4.1 %, 5.7 %, and 2.2 %, respectively, and the backward EW one is mainly transmitted. To optimize AAT, a quasi-periodic Octonacci sequence-aligned SCMPC is introduced. The results show that the maximum OB of forward absorption and backward transmission is 428.3 ∼ 670.5 THz and RB is 44.1 %, achieving favorable broadband AAT. In addition, the effects of temperatures, dielectric thicknesses, and stacking numbers on AAT are also investigated in detail. In conclusion, AAT has promising applications in unidirectional optical transmission, photodiodes, optical isolators, etc.

Keywords

• Superconductor ceramics
• Metastructure-photonic crystals
• Broadband asymmetric absorption-transmission
• Quasi-periodic cascading structure
• Rasorber