Broadband Terahertz Polarizing Beam Splitter Based on a Graphene-Based Defective One-Dimensional Photonic Crystal

Ziba Saleki,Yurui Fang,Samad Roshan Entezar

doi:10.1109/jphot.2019.2935084

Ziba Saleki, Yurui Fang + Show 1 more

Open Access

https://doi.org/10.1109/jphot.2019.2935084

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Abstract

Seeking operative terahertz (THz) devices has always stimulated considerable attention. Of particular interest is the THz beam splitter. Here, a tunable THz polarizing beam splitter (PBS) is proposed based on a graphene-embedded quarter-wave stack with a central defect layer of air. The spectral performance of the structure is investigated by the transfer matrix method. It is found that the electromagnetic waves can be decomposed into two separate polarized waves at incident angles greater than the critical angle. Furthermore, it is shown that a new kind of Brewster angle is found at the low THz frequencies due to the existence of the graphene nano-layers. The appearance of this angle which we call it the graphene induced Brewster angle results in the separation of TM- and TE- polarized waves at the low THz frequencies (f 200 dB) for TM waves with frequency f <; 2 THz is achieved by increasing the chemical potential to 0.5 eV. Moreover, this structure can exhibit extremely high extinction ratio for TE waves with high THz frequencies. Finally, the degree of polarization equals to one is reported for the PBS proposed here. This structure offers the opportunity to realize a high-efficiency PBS with very high extinction ratios at the broadband THz frequency.

Highlights

Since their discovery, photonic crystals (PCs), artificially designed periodic dielectric materials, have become an indispensable technology across the entire field of optical physics because of their ability to control and confine of electromagnetic waves [1], [2]
The analysis of the proposed polarizing beam splitter (PBS) is confirmed by the Finite Element Method (FEM) simulations that were performed with the commercial software COMSOL 5.2
In the present paper, we theoretically investigate the optical properties of a graphenebased defective 1D-PC in which Si and Si O 2 are used as the high index and low index dielectric alternating layers and graphene nano-layers are embedded between adjacent dielectric layers

Summary

Introduction

Photonic crystals (PCs), artificially designed periodic dielectric materials, have become an indispensable technology across the entire field of optical physics because of their ability to control and confine of electromagnetic waves [1], [2]. Some interesting peculiarities of the defect modes are investigated and it is shown that the structure can support a defect mode at the graphene induced PBG for wide defect layers In their recent works, they reported omnidirectional broadband THz filter based on a one-dimensional Thue-Morse quasiperiodic structure containing graphene nano-layers. They reported omnidirectional broadband THz filter based on a one-dimensional Thue-Morse quasiperiodic structure containing graphene nano-layers They showed that the mentioned structure can act as a polarizing beam splitter [28].

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