Monolayer WS₂ Based Electro-absorption Modulator

The electro-absorption modulator is one of the key components in the modern optical fiber communication system.Electro-absorption modulators made of graphene materials have received extensive attention from the scientific team,but the zero-band gap of graphene hinders its application in the semiconductor field.Monolayer WS₂ is similar to graphene,because of its structural characteristics and optical properties,which has broad prospects in the application of electro-absorption modulators.In this study,a monolayer WS₂ electro-absorption modulator based on a Ga N waveguide was developed using the simulation software COMSOL Multiphysics.The monolayer WS₂ was covered on the top of the optical waveguide model,and a strong interaction between monolayer WS₂ and light is obtained.Different voltages are applied to change the refractive index of WS₂to achieve modulation.The research results show that the monolayer WS₂-based electro-absorption modulator can achieve 153 GHz 3-d B modulation bandwidth,around 70%modulation depth with 108)-long active region.The main contents of this article are as follows:(1)The research about electro-absorption modulators is introduced.The electrical and optical properties and preparation methods of WS₂ materials are presented in detail.And the advantages and prospects of monolayer WS₂ materials is analyzed used in electro-absorption modulators.(2)A monolayer WS₂ electro-absorption modulator based on Ga N waveguide is designed.The waveguide mode and energy field distribution characteristics were explored,and the optical limiting factor was calculated.The effects of waveguide width,waveguide height,material and thickness of isolation medium on the imaginary part of effective mode refractive index of TE mode and TM mode waveguide are studied.An optimal modulator size is developed.(3)Theoretical analysis of the monolayer WS₂ electro-absorption modulator were carried out.The 3-d B modulation bandwidth,modulation depth,and absorption of the electro-absorption modulator in TE and TM modes were studied.The loss and chirp characteristics are compared and analyzed with the corresponding parameters of the four-layer graphene electro-absorption modulator,and the performance of the modulator is analyzed in detail.It is concluded that the electro-absorption modulator on WS₂shows superior characteristics in terms of 3-d B modulation bandwidth,modulation rate,and insertion loss.The work of this paper paves the way for the theoretical and simulation research of electro-absorption modulators based on WS₂ and other two-dimensional materials.