Research On Electric Field Measurement Technology Based On Multimode Waveguide

In the high-speed developing information age,electric field measurement has gradually played a key role in the power industry,communication system,aerospace and so on.Commonly electric field measurement sensors include capacitive,field mill and photoelectric.Among them,the lithium niobate(LiNbO3,LN)optically electric field sensor has the superiority of large bandwidth,wide dynamic range,and small volume.In addition,the lithium niobate electric field sensor contains few metal structures inside,and even does not contain metal electrodes inside,so the interference introduced by the electric field to be measured is small during measurement.Therefore,this type of sensor is often diffusely used in many fields,and even the study of physical mechanisms such as corona gap discharge can’t be separated from it.High-performance optically integrated sensors have sparked a wave of research.This thesis the multi-mode interference phenomenon is used to measure the electric field.The main work includes the following parts:1、Firstly,the research background of electric field measurement is introduced.According to its application in electric power industry,communication transmission and space industry,the necessity and importance of electric field sensor research are explained.Then,taking the timeline of the development process of electric field sensors as the axis,introducing the development of sensors at home and abroad in detail,and the main principles,characteristics and development overview of optical waveguide electric field sensors are mainly introduced.2、Research on electric field identification based on multimode interference speckle imaging.Combined with the characteristics and laws of multimode interference,detailed analysis of the input-side single-mode waveguide mode field is presenting,and the final input size of the waveguide is fixing.Then,the size of the waveguide in the multimode interference area is optimized,and the appropriate width and length are selected to ensure the usability of the interference results.Finally,the identification of the electric field to be measured is completed according to the designed multimode waveguide structure.The final simulation results show that within the electric field test range of 500 V/m～10~6V/m,the sensitivity is 500 V/m.The sensor can be used for testing low-frequency variable electric field or electrostatic field.3、Research on electric field measurement based on multimode interference.For general application scenarios,by using the special MMI structure,the output port power changes in the same direction caused by temperature,and the output port power changes in the opposite direction caused by electro-optic effect.The balanced photodetector receives the output signal,which not only eliminates the influence of temperature,but also amplifies the power of the output signal.During the simulation,the voltage probe is used to obtain the magnitude of the induced voltage under different external electric field environments,and its linear relationship is obtained.According to the relationship between the external electric field environment and the output port power of the multimode interferometer,the linear expression of the power and the measured electric field is given to realize the measurement of the electric field.