Polarization Converter with Controllable Birefringence Based on Hybrid All-Dielectric-Graphene Metasurface

Abstract

Previous studies on hybrid dielectric-graphene metasurfaces have been used to implement induced transparency devices, while exhibiting high Q-factors based on trapped magnetic resonances. Typically, the transparency windows are single wavelength and less appropriate for polarization conversion structures. In this work, a quarter-wave plate based on a hybrid silicon-graphene metasurface with controllable birefringence is numerically designed. The phenomena of trapped magnetic mode resonance and high Q-factors are modulated by inserting graphene between silicon and silica. This results in a broader transmission wavelength in comparison to the all-dielectric structure without graphene. The birefringence tunability is based on the dimensions of silicon and the Fermi energy of graphene. Consequently, a linear-to-circular polarization conversion is achieved at a high degree of 96%, in the near-infrared. Moreover, the polarization state of the scattered light is switchable between right and left hand circular polarizations, based on an external gate biasing voltage. Unlike in plasmonic metasurfaces, these achievements demonstrate an efficient structure that is free from radiative and ohmic losses. Furthermore, the ultrathin thickness and the compactness of the structure are demonstrated as key components in realizing integrable and CMOS compatible photonic sensors.

Efficient Optical Reflection Modulation by Coupling Interband Transition of Graphene to Magnetic Resonance in Metamaterials

“…In the past few years, much effort has been made to actively manipulate the transmission, reflection, or absorption spectra of electromagnetic waves, which is based on electrically tunable surface conductivity of graphene, in a very wide frequency range including microwave [5,6], terahertz (THz) , infrared , and visible regime [66][67][68][69]. Such graphene-based active manipulation of electromagnetic waves is under external electrical stimulus without re-building-related structures, which aims to efficiently modulate the amplitude [5, 7-21, 34-57, 66-72], phase [6,[22][23][24][25][26][27][28][58][59][60][61][62], and polarization [29-33, [63][64][65] of electromagnetic waves. The three kinds of electromagnetic wave modulators are the most important for signal processing in free-space optical communications [1][2][3][4].…”

A Novel Reconfigurable Metasurface with Coincident and Ultra-Wideband LTL and LTC Polarization Conversion Functions

“…The implementation of the existing reconfigurable polarization converters can be divided into two methods. One method is to change the dielectric materials [16][17][18][19][20][21], the other is to change effective metal structure by using electronic devices [22][23][24][25][26][27][28][29][30][31][32][33]. The former method uses materials such as liquid crystals [16], graphene [17], [18], metal fluid [19], [20], vanadium oxide (VO 2 ) film [21] to replace the traditional metal and dielectric materials, this method has the characteristics of high frequency band and difficult fabrication.…”

“…One method is to change the dielectric materials [16][17][18][19][20][21], the other is to change effective metal structure by using electronic devices [22][23][24][25][26][27][28][29][30][31][32][33]. The former method uses materials such as liquid crystals [16], graphene [17], [18], metal fluid [19], [20], vanadium oxide (VO 2 ) film [21] to replace the traditional metal and dielectric materials, this method has the characteristics of high frequency band and difficult fabrication. In contrast, the latter method uses PIN diodes [22][23][24][25][26][27], varactor diode [28], [29] and MEMS switch [30], [31] which have the characteristics of easy fabrication, good electronic control performance, flexible structure and high efficiency.…”

Reconfigurable Multifunctional Metasurface Hybridized with Vanadium Dioxide at Terahertz Frequencies

“…Recent efforts have started to be devoted to the design of the reconfigurable multifunctional metasurface by hybridizing metasurfaces with tunable metaparticles, such as the vanadium dioxide (VO 2 ), graphene, liquid crystal, micro-electromechanical system (MEMS), varactor diode and PIN diode [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. It is widely known that manipulation of the polarization state of electromagnetic (EM) waves [ 36 , 37 , 38 , 39 , 40 , 41 ] and the switch of the amplitude of transmission and reflection [ 42 , 43 , 44 , 45 ] are of paramount importance in both THz scientific and engineering applications. Thus, it makes a great significance to integrate these two functions into a single metasurface.…”