Research On Linearization Of Silicon-Based Electro-Optic Modulator Based On Microring

With the development of silicon-based photonics,the integration of the advantages of the respective fields of silicon-based photonics and microwave photonics has become an important research direction in recent years.In microwave photonic links（MPL）,the optical modulator,as one of the core devices,serves to encode RF signals into the optical domain with high fidelity for applications such as wireless access networks and remote transmission processing.The linearity of the modulator has a direct impact on the system performance,and the improvement of linearity is still a hot research topic.This thesis addresses the optical domain linearization technique,the optical transfer function linearization method.The linearity of the transfer function is improved by using a conventional Mach-Zehnder Modulator（MZM）sinusoidal transfer function and Ring resonator modulators（RRM）superlinear phase modulation.Firstly,the linearization principle is analyzed to give a highly linear modulation scheme for single Micro-ring MZM under ideal conditions.The second order of the device modulation curve expansion is made zero by DC bias,and then the third order term is made zero by reasonably setting the coupling and transmission coefficients of the RRM.The second-order and third-order terms,which mainly affect the linearity of the modulation,are eliminated,and the DC bias and coupling and transmission coefficients at this point are the optimal conditions for high linear modulation（τ=0.268）,and the same analysis gives the optimal conditions for the modulation of the dual microloop（τ=0.268）.Then,under the consideration of loss and RRM processing error,it is necessary to achieve RRM coupling,adjustable transmission coefficient,modulation optimal condition matching,and then single microring linearization scheme for optimization.It is proposed to tune the operating wavelength and coupling conditions by embedding voltage-tunable graphene inside the waveguide,and to always find theτandΔφ（τ）,that enable the device to achieve high linearity conditions in the operating wavelength range of 1.554μm-1.556μm,along with the elimination of the second-order and third-order terms.Finally,based on this optimization scheme,a polarization-independent high linear micro-loop modulator is further extended to propose a polarization-independent high linear micro-loop modulator,which realizes the conversion of TM0 mode at the incident end of the device to TE0 mode before entering the modulation arm to participate in the modulation,eliminating the polarization-independent effect of the modulator,followed by the characterization of some performance parameters of the device.The insertion loss in TE0 and TM0 modes are 3.1 dB and 6 dB,respectively.The modulation depth is greater than 24 dB in the 1.554μm-1.556μm operating wavelength range,and the spurious-free dynamic range is 116.5 dB?Hz^2/3-118.3dB?Hz^2/3.