Electro-Absorption Optical Modulator Based on Graphene-Buried Polymer Waveguides

Tianhang Lian,Shijie Sun,Donghai Niu,Xibin Wang,Daming Zhang,Kaidi Yang,Minghui Jiang

doi:10.1109/jphot.2020.3011749

Tianhang Lian, Shijie Sun + Show 5 more

Open Access

https://doi.org/10.1109/jphot.2020.3011749

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Abstract

By exploiting the electro-absorption characteristic of graphene, we proposed and theoretically demonstrated an electro-absorption optical modulator (EOM) based on the graphene-buried polymer waveguides. By burying the graphene layers inside the polymer waveguide, acquiring a strong graphene-light interaction when the graphene layers buried in the center of core, which bring about an important change of the optical mode and effective mode index in the waveguide. The width of the graphene capacitor was also optimized to enhance the bandwidth of the device. Calculations show that the proposed EOM can realize 29 dB extinction ratio, 7 dB modulation depth and 42 GHz bandwidth with an 800 μm-long active region. The required switching voltage form its minimum to maximum absorption state is 1.6 V and 1.55 pJ/bit energy consumption can be achieved. The proposed modulator can remedy the lack of high-speed optical modulator on the passive polymer waveguide and have a potential application for polymer-based photonic integrated circuits.

Highlights

Electro-optic (EO) modulator is a significant optical device for photonic system on chip in fiberoptic networks and photonic integration system [1]
The graphene layer was modeled as an anisotropic material, and the in-plane conductivity of graphene is different from out-of-plane conductivity
In order to enhance the interaction between graphene layer and light, we buried the graphene layers in the center of waveguide core

Summary

Introduction

Electro-optic (EO) modulator is a significant optical device for photonic system on chip in fiberoptic networks and photonic integration system [1]. It works by loading electric signal with specific information encoding onto the beam of light and adjusting the absorption or phase of the guided optical signal in the waveguide. In the past few decades, many kinds of EO modulators based on different material systems have been investigated, such as the InP modulator, LiNbO3 modulator, silicon modulator and polymer modulator [3]–[6]. Compared with other material systems, polymer EO modulators have recently become popular due to polymer advantages over traditional optical materials, such as low cost, simple fabrication process, large EO coefficient, high coupling efficiency with optical fiber, Vol 12, No 4, August 2020

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