Research On Graphene-based Optoelectronic Modulator

With the rapid development of information technology,it has led to an explosive increase in the amount of information processed,and it has also brought the huge challenge to the current optical fiber communication network.The key component of the optical fiber communication system is the optoelectronic modulator.Its most important function is to modulate the electrical signal for transmitting information onto the optical carrier.The disadvantages of traditional optoelectronic modulators mainly include the large size,the slow modulation rate,and the high cost.As a two-dimensional new material with zero band gap,graphene has the advantages of the ultra-fast carrier mobility,the high transparency and the compatibility with CMOS processes.Therefore,the new optoelectronic modulators based on graphene materials have become the domestic and foreign research hotspots.This paper mainly studies the electro-optical modulation characteristics of graphene,and designs two new structures of graphene-based optoelectronic modulators.By optimizing its structure,and its performance parameters are finally calculated.The specific research work of the full text is as follows:(1)The research background and significance of optoelectronic modulators based on graphene materials are reviewed,and the current domestic and foreign research status and characteristics of graphene optoelectronic modulators with three mainstream structures are analyzed.(2)The electro-optical modulation characteristics of graphene are studied,mainly including the electronic energy band structure,the electrical conductivity and the effective refractive index of graphene.On this basis,the relationship between the chemical potential energy of graphene and the applied driving voltage,the conductivity of graphene and the effective refractive index of graphene were studied separately,and the working mechanism of graphene optoelectronic modulation was revealed.(3)A graphene optoelectronic modulator based on double ring resonator is designed.Utilizing the electrical tunability of graphene,the dynamic optoelectronic modulation is achieved by applying different driving voltages to the electrodes at both ends.The F-P resonant cavity is formed by the double ring resonant cavity structure,which enhances the modulation efficiency of the device.The simulation software COMSOL is used to analyze the relationship between the radius of the ring,the waveguide material and the output characteristics of the device.By optimizing the geometric parameters of the device,the best performance index of the device is obtained.(4)A polarization-independent optoelectronic modulator based on graphene ridge structure is proposed.The double-layer graphene ridge structure can interact with the light field in both the vertical and horizontal directions,so that the modulator can achieve the same modulation effect for both TM and TE modes.The COMSOL software was used to study the changes of the real and imaginary parts of the effective refractive index of the modulator in TM and TE modes.By optimizing the structure of the modulator,the extinction ratio of the device can reach up to 110 d B and the modulation bandwidth is173.78 GHz.The insertion loss is only 0.0338 dB.