Abstract
In the field of modern optical communication systems and photoelectric detection, new components with complex functions and excellent performance are urgently needed. In this paper, a graphene-based parity–time (PT) symmetry structure is proposed, which is achieved by preparing the graphene layer on the top of a PT-symmetry photonic crystal. The transfer matrix method was used to calculate the absorptance of graphene, and a unique amplified absorption effect was found. Meanwhile, the peak value and wavelength position of the absorption can be modulated via the applied electric field. The results show that by adjusting the negative square-wave electric field from −3.5 × 10−5 to −13.5 × 10−5 V/nm (or the positive square-wave electric field from 2 × 10−5 to 11 × 10−5 V/nm), the proposed structure can achieve in-phase (or out-phase) enhanced absorption for the communication wavelength 1550 nm, with the absorption of graphene from 17 to 28 dB (or 30 to 15 dB) corresponding to the square-wave modulation electric field change. The modulable absorption properties of graphene in the structure have potential in optoelectronic devices and optical communication systems.
Highlights
Graphene has been widely studied by scholars for its special electrical and optical properties
Li et al provided a comprehensive review of graphene synthesis methods and its potential industrial implementations [7]; the literature data indicated that a large amount of high-quality graphene can be synthesised by oxidative exfoliation–reduction, liquid-phase exfoliation (LPE) and chemical vapor deposition (CVD), which lays the foundation for the commercial application of graphene
Therein, the underlying PT-symmetry structure is mainly composed of the gain-loss dielectric layers and the embedded LiNbO3 crystal, and the graphene layers are placed on the top of the PT-symmetry structure
Summary
Graphene has been widely studied by scholars for its special electrical and optical properties. Angle Spectroscopic Ellipsometry (VASE), and the estimated carrier density from optical conductivity data reached 7.8 × 1013cm2 [15] Those studies bring inspiration for the design of graphene-based optoelectronic devices. Based on the electro-optic effect of LiNbO3 crystal, graphene absorption can be modulated regularly by modulated electric fields. The proposed design exhibits ultrastrong and modulable light absorption compared with the traditional 1D-PC structure and the complex 1D-PC with special material layer. These findings have certain reference significance for the design of tunable absorbers, photodetectors, optical communication devices and related optoelectronic devices
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