Research On Key Technologies Of Linearization Of Silicon-based Composite Waveguide Modulator

With the increasing demand and application of microwave wireless communication,the communication system faces the challenge of transmitting and processing huge amount of data.Radio-over-Fiber(ROF)system is one of the main technologies to solve these problems.The linearity of the electro-optic modulator as a core component of ROF system can seriously affect the signal transmission,processing and spurious-free dynamic range(SFDR)of the system.At the same time,as a new two-dimensional material,graphene plays an increasingly important role in electro-optic modulator with its excellent electro-optic characteristics.This thesis analyzes the principle of the most widely used optical domain linearization technology——Microring-Assisted Mach-Zehnder Modulator(MRAMZM),then analyzes and discusses the nonlinear distortion suppression method of the device,and obtains the MRAMZM high linearity optimal solution condition.On the basis of this,two kinds of high linearity realization schemes based on graphene wavelength-tunable are proposed for TE0 mode and TM0 mode,and the performance and linearity index MRAMZM the two kinds are analyzed.In this thesis,several applications of graphene-based electro-optic modulators are introduced,and the performance of each modulator is analyzed.A polarization-independent electrical absorption modulator is proposed,and the modulator achieves the same modulation effect for TE0 mode and TM0 mode by optimizing the structure of graphene in the waveguide.For a 100?m-long waveguide,different chemical potentials of graphene are selected as the“ON”and“OFF”state points to achieve an ER of about20 dB,and the gap between the ER of TE mode and TM mode is less than 1.2dB.And at the"ON"state point,the dependency of these two polarization states is lower than0.112dB.Then this thesis introduces the linearity indicator of electro-optic modulator SFDR,and analyzes the SFDR_IMD3 of MZM is 97 dB·Hz^2/3.Meanwhile,an ideal scheme of high linearity of MRAMZM is analyzed.After optimizing the parameters of the modulator,the optimal SFDR_IMD3 is 117.65 dB·Hz^2/3.Finally,this thesis analyzes the high linearity optimal solution of MRAMZM with micro-ring loss,and propose two high linearity MRAMZM based on graphene wavelength-tunable for TE0 mode and TM0 mode.The MRAMZM we designed for TE0mode can achieve the elimination of second-order and third-order nonlinear distortions in the 2 nm wavelength range(1.5543?m to 1.5562?m),SFDR_IMD3 is 114.61 dB·Hz^2/3;The MRAMZM we designed for TM0 mode achieves linearity improvement of the modulator in the range of 5 nm(1.5468?m-1.5516?m),SFDR_IMD3 is around 114 dB·Hz^2/3.At the same time,the extinction ratio of the device is more than 26 dB by using an adjustable beam splitter based on graphene.