Design Of A High Speed Traveling Wave Modulator Base On Graphene And Microfiber

High performance modulator is crucial hardware for implementing electrical signals onto optical wave,and it has become the core of optical communication network.Efficient external modulation has become the mainstream of commercial modulation technology.The Li Nb O3 modulator that utilizes the linear electro-optic effect is far from the requirements of on chip integration for the size of device is up to centimeter level.The rate of silicon optical modulator based on the plasma dispersion is mainly limited by the device's resistance and capacitance time constant.Existing modulators are not enough to meet the stringent demands of high level integration and fast rates.Therefore,researching efficient light modulation devices is particularly important.Based on the analysis of silicon traveling wave optical modulator,we propose high speed traveling wave electro-optic modulators that combine graphene with microfiber.It has the advantages of compact structure,low power consumption and fast response.We have verified the excellent characteristics of the modulator by simulation.The dissertation summarizes the development of graphene optical modulator,current research situation and future development trend.We briefly introduce the basic parameters of measuring the modulator and the classification of the modulator.We analyze the working mechanism of silicon traveling-wave optical modulator of carrier depletion type,which is the foundation for the next research on the modulator of graphene combined with the micro-fiber.When high-speed optical modulator based on graphene and micro-fiber is being researched,the theoretical parameters of electro-optic effect of graphene are introduced,and we analyze the optical properties of microfiber.The optical property of graphene-microfiber is simulated by finite element method.The results show that the real part of effective refractive index changes greatly and the imaginary part almost remains constant when the Fermi level of graphene changes from 0.5 e V to 0.9 e V,this property can be better applied to the optical phase modulator.After optimizing the fiber diameter and the graphene layer number,modulator's parameters such as light group refractive index,attenuation coefficient,normalized light output and the quality factor of modulation phase efficiency for electro-optic modulator are calculated by effective refractive index.In this dissertation,we studied the applied voltage of modulating device and the frequency response factor of lumped electrode modulator in the process of research on the bandwidth performance of optical modulator.We proposed the use of traveling wave electrode to overcome the limitation of RC time constant.In this dissertation,3D full-wave electromagnetic simulation is used to optimize the structure of the modulator electrode by reducing the microwave loss,increasing the impedance matching,and matching microwave with the speed of the light group.As a result,the phase of the light meet a shift of ? at a working wavelength of 1550 nm,the length of the interaction between the micro-fiber and the graphene 1.372 mm with the modulation voltage only 4.95 V,the bandwidth of electro-optic modulation up to 82 GHz.