Tunable Terahertz Perfect Absorber and Polarizer Based on one-Dimensional Anisotropic Graphene Photonic Crystal

Abstract

In this article, a new tunable absorber and polarizer using one-dimensional anisotropic graphene photonic crystal (1D AGPC) is proposed for terahertz applications. The optical properties of the 1D AGPC structure is obtained through the transfer matrix method (TMM) calculations. In our design, a single defect layer is introduced in the 1D AGPC structure to increase its absorption. The absorption coefficient is further modified by optimizing the AGPC parameters such as the number of photonic crystal periods, the defect layer thickness, and the chemical potential of graphene. The modified structure can provide perfect absorption with a narrow bandwidth of 0.05 THz. On the other hand, considering the anisotropic optical properties of graphene, polarization dependence of the absorption coefficient is investigated. This feature of the structure can be employed to realize a tunable terahertz polarizer by adjusting incident angle at Θ0 = 80°. In this way, high tunable polarization extinction ratio of 6.1 dB to 11.63 dB with respectively very narrow bandwidth of 0.031 THz to 0.023 THz are obtained. The maximum insertion losses within the tunable frequency range are as low as 0.023 dB and 0.031 dB. Hence, our design may have potential applications in narrow-band optoelectronic devices at the terahertz frequency range.