Research On Graphene-silicon Hybrid Optoelectronic Devices In Optical Modules

Recently,with the development of new technologies such as artificial intelligence and 5G,the demand for data traffic has been increasing day by day.The maximum exchange rate of the existing optical communication technology,100 Gbps,has been unable to meet the demand.As a result,optical module,the core unit of the optical communication network,will become a hot issue of worldwide concern in the next few years.The research on the key components of the optical module,the electro-optic modulator and the photodetector,will also become a research hot spot for scholars from all over the worldHowever,due to the inherent limitations of traditional silicon materials such as low electron mobility(only 1350 cm2V-1s-1)and indirect band gap structure,the modulation rate of pure silicon-based electro-optic modulators is difficult to further increase,and the working wavelength of photodetectors is limited to visible light and some infrared bands.In order to overcome the above problems,scholars from all over the world have tried to integrate various materials with silicon-based chips to extend the potential of silicon-based optoelectronic devices.Among them,graphene,a two-dimensional nanomaterial,has attracted wide attention due to its excellent optical and electrical characteristics such as ultra-high electron mobility(20000 cm2V-1s-1)and direct band gap structure.It has injected fresh energy into the research of electro-optic modulators and photodetectors.Nevertheless,there are still many problems to be solved in the research of graphene-based optoelectronic devices:(1)For electro-optic modulators,due to the monoatomic thickness of graphene,the effective interaction area between the light field and graphene is relatively small,which results in low modulation efficiency;(2)For photodetectors,due to the two-dimensional sheet structure of graphene,the absorption rate for normal incident light is only 2.3%,which makes it very difficult to improve the responsivity of photodetector.In order to overcome the above challenges,the following researches have been done in this paper:(1)A graphene-based hybrid plasmonic modulator has been proposed in this paper.The strong modes confinement of hybrid plasmonic waveguide makes it possible to enhance the light-graphene interaction in graphene-based modulators.Therefore,the theoretical modulation efficiency has been improved to 0.417 d B/?m in the proposed modulator.Then,a modulator sample was fabricated and a modulation depth of 1.08 d B was obtained in experimental measurement.(2)A graphene-based tri-slot photodetector has been proposed in this paper.By adopting a pure silicon tri-slot waveguide,the absorption of incident light is enhanced while the waveguide loss still maintains at a low level.Through the experimental measurement of the proposed photodetector,the enhanced effect of tri-slot waveguide was verified,and a 2.9 m A/W responsivity was obtained.