The Preparation And Performance Study Of Electro-optic Modulator Based On Graphene Supercapacitors

The optical modulator is one of the key devices in integrated optics and is an important device for high-speed optical communication,whose performance is directly related to the optical signal transmission quality.Optical modulators based on semiconductors,lithium niobate,or polymers have been widely used in this field.However,they still have high power consumption and high manufacturing costs,while the response rate and modulation depth are limited by the material itself.Graphene,a novel two-dimensional material,is easy to generate the redistribution of electrons and holes with the external electric field,which lead to the changing of Fermi level.This change can alter the absorption of graphene,which provide potential applications for optical modulator.In this paper,the preparation of graphene-based optical modulator based on supercapacitor structure and its variable angle modulation performance are studied.Multi-angle modulation properties of electrolyte gated graphene visible-infrared modulators have been examined.Both transmission and reflection geometries have been studied,and the results show that all the modulations of these devices are gate voltage and wavelength dependent.Maximum modulation depths for transmission device?3%and reflection modulator?5%are obtained.Theoretical analysis based on the different tangential and normal optical responses of the quartz/graphene/eletrolyte interface has been used to explain the phenomena,which indicated a common effect of p-polarized and s-polarized light.This work offers useful insight into a multi-angle application of the graphene-based optical modulator in visible-infrared region.In order to avoid the shortcoming of electrolyte leakage and short working-life,we used a gel-like solid electrolyte to replace the aqueous electrolyte,and the quartz substrate was replaced by PET to prepare a flexible graphene-based optical modulator.The experimental results show that the modulation depth increases with the promoting voltage,and the modulation depth of the long wave band is larger than that of the short wave band.This indicates that the mechanism of the flexible graphene-based optical modulator may similarly result from the blocking of interband transition.