Research On The Graphene-based Optical And Electrical Devices As Well As Their Key Technologies

The optoeletronic technology plays an important role in the modem imformation technology.With the rapid development of imformation technology,optical and electrical devices are required to have the features of high speed,low power consumption,small footprint and high integration.However,the development of optical and electrical devices are limited by the optical,electrical,thermal and mechanical properties of conventional material.To satisfy the requirement of imformation technology,new material is expected to be employed in the design of optical and electrical devices.Graphene which is a kind of novel two-dimensional nano material,is considered as one of the most promising materials because of its excellent optical,electrical,thermal and mechanical properties.However,there are still a lot of scientific and technological challenges in the design of graphene-based optical and electrical devices:(1)Low efficiency,for example,the modulation efficiency of graphene-based modulator is low due to the weak "electromagnetic wave-graphene" interaction;(2)It is diffcult to obtain nonvolatility,for example,in order to keep absorption performance stable,a constant voltage is required in the graphene-based tunable absorber.Once the voltage is removed,the absorption performance will deteriorate quickly,which means the absorption performance is volatile;(3)Narrow bandwidth,for example,when the group index of graphene-based slow light waveguide is high,its slow light bandwidth is usually narrow.In order to overcome the challenge one,a graphene-based single slot HSPP modulator and a graphene-based double slots HSPP modulator are proposed respectively.By employing the HSPP waveguide to improve the light-graphene interaction,the modulation efficiency can increase from-0.1 dB/?m(traditional graphene-based silicon modulator)to 1.23 dB/?m(graphene-based single slot HSPP modulator)and 0.7 dB/?m(graphene-based double slots HSPP modulator).Meanwhile,a graphene-based HSPP modulator is fabricated in this paper.The experiment results show that this modulator can work in a relatively wide wavelength range(1530 nm?1570 nm).Moreover,a graphene-based silicon ring modulator is designed and fabricated.Its experimental results of extinction ratio(?13.9 dB)is larger than that of the traditional graphene-based silicon ring modulator(?2.2 dB).Meanwhile,a terahertz modulator based on "silicon-self-biased graphene structure-silicon" sandwich waveguide structure is also designed in this paper.Its largest modulation depth in measurement is 21.86%,which is larger than that of some traditional graphene-based terahertz modulators.In order to overcome the challenge two,a tunable absorber based on nonvolatile floating-gate graphene structure is proposed.The absorptivity can be tuned by the external voltage and the absorptivity can keep nearly constant after the external voltage is removed.Moreover,the absorption bandwidth(?60 GHz)and the absorption performance stability under different incidence angles of the proposed absorber can be better than those of traditional graphene-based tunable absorbers.In order to overcome the challenge three,a novel graphene-based tunable slow light waveguide is proposed.Benifited from the effective index of graphene SPP mode,which is much larger than the effective index of traditional waveguide mode,and the good dispersion property of periodic triangle air hole,a large group index(?163)and a wide slow light bandwidth(?94.4 nm)can be obtained at the same time.