Abstract
In this paper, we propose a polarization-independent optoelectronic modulator based on the electrical absorption effect of graphene. Firstly, we use the simulation software COMSOL Multiphysics to design the structure, and find via changing the applied voltage on both ends of the graphene that the equivalent refractive index of graphene can be changed, thus changing the light absorption capacity of the modulator. The waveguides in the transverse magnetic (TM) and transverse electric (TE) modes have almost the same extinction coefficient by making a double-layer graphene ridge structure in the center of the silicon-based waveguide, which can achieve approaching modulation depth in the TM and TE modes. At 1550 nm wavelength, the two-dimensional cross-section of the structure is analyzed by the FEM method using COMSOL Multiphysics to obtain the effective refractive index of the structure. The simulation results show that when the distance between the double-layer graphene isolation layer is d = 20 nm, the TE and TM modes can achieve extinction ratios up to 110 dB over the wide communication band by selecting appropriate “ON” and “OFF” switching points. The bandwidth is 173.78 GHz and the insertion loss is only 0.0338 dB.
Highlights
The modulator made of traditional photoelectric materials has been widely used in the field of optical communication [1,2,3,4]
Placing the graphene ridge structure in the center of the waveguide enhances the interaction between the light and graphene
The paper presents a polarization-independent optical modulator based on the doublelayer graphene ridge structure
Summary
The modulator made of traditional photoelectric materials has been widely used in the field of optical communication [1,2,3,4]. 90-degree bend to the inside of the waveguide core layer by using the principle of taking both the horizontal and vertical directions of the graphene layer into consideration, thereby making a graphene-based polarization-independent light modulator. Shengwei Ye et al [25] deposited a sloped trapezoidal double-layer graphene layer in the middle of the silicon waveguide, so that the graphene can interact with the polarized light field in both the horizontal and vertical directions, and achieved polarization-independent modulation. This paper presents a polarization-independent optoelectronic modulator based on the graphene absorption effect and simulated by COMSOL Multiphysics software. Because graphene can fully interact with the light field in both the horizontal and vertical directions, the TM and TE modes have the same extinction coefficient, achieving the purpose of polarization independence. The designed modulator in this paper provides a theoretical foundation for the further development of optical communication
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