Integrated Optical Waveguide Current Sensors Measure The Pulse Current

Not only sensor is an important base in the new technological revolution and information society,but also it is the pioneer of modern science and technology.Along with the development of modern measure,control and automatics,sensor is more and more remarkable in every field,and becomes the key component in system.Various types of waveguide production based on crystal materials have rapid development in optical communications and information processing,and optics waveguide sensor is one branch of them.It applies not only in fiber communication and sensing,but also in stress,pressure,temperature,current and chemical gas sensing etc.This thesis is a research about integrated optics waveguide sensor which is used in high voltage power industry for sensing current.Power industry is the basic of one country's economic construction,and it plays a vital role in the national economy.With the rapid economic development,there is a growing demand for electricity,especially as the development of high-voltage high-current,traditional oil-filled current transformer has not well adapted to the needs of industrial,so both domestic and international company are committed to the research of low price,simple,safe and reliable new high-voltage high-current sensing system, what studied in this paper about hybrid optical current sensor is a good choice.In this paper,hybrid optical sensors are made up of two parts,one is Rogowski coil circuit and the other part is Mach-Zehnder interference optical waveguide modulator, Rogowski coil circuits connected to the electrode of the output waveguide modulator. Rogowski coil is trapped in the sensing large current conductor,voltage induced by the coil has linear relationship with the sensing current,and then the voltage adds to the electrode of the modulator,the effect is that incident laser signal is modulated,using photodiode to receive the output optical intensity.Current characteristics of the conductor can be gotten by the analysis of the output intensity in the waveguide.This is the basic principle of the current sensor. As to Rogowski coil,two structures including rectangular and circular section are analyzed.Ratio coefficient of the induced voltage and sensing current is obtained, which is the formula for calculating the coefficient of mutual inductance.For different relationship between voltage and current,two corresponding equivalents circuits are studied,one is simple circuit structure and the other is integral structure,and their steady-state response and transient response which applies to different situation are analyzed.Select appropriate size of the current and frequency of a given circuit model parameters to do analysis of the simulation,and the analysis of the results are fully in line.Another part of the sensor is Mach-Zehnder interference type optical waveguide modulator,principle of the modulator is analyzed which led to the principle of the designed optical waveguide current sensor.Theoretical formula of the sensing current and output intensity of the waveguide are derived,and at the same time,phase bias is obtained by using refractive index unsymmetrical structure,simulation phase is 76.93°, it is in line with the request,then output light intensity has linear relationship with the sensing current approximately.Following study is about how to connect the system between the coil and the modulator,and then parameters of the modulator are analyzed. Using these data sensitivity and frequency characteristic of the system are calculated.At last,simulating voltage on the electrode of the modulator by OptiBPM software,results show that the former theory is correct.In this paper,the main jobs are the theory calculation and design of the optical waveguide sensor current,and also the designed structure is analyzed and simulated which are in line with the theory.The sensor applies for measuring large current in high voltage environment,current range is from 10 A to 8000 A and frequency range is 0 Hz to 5000 Hz.These results not only provide the basic theory for further experiment but also have important theory and practical significance.