Research On Integrated Optical Waveguide Three-Dimensional Pulsed Electric Field Sensing System

Integrated optical waveguide sensor has advantages of compact size, anti-electromagnetic interference, wide bandwidth and negligible original field interference. As a result, it has potential capability to be used to detect intense EMP signals. Based on the electro-optic modulation technology of LiNbO3 (LN), an integrated optical waveguide sensing system for measurement of pulsed electric fields is researched in this thesis. The main contents include:1. Analysis of the principle of integrated optical waveguide electric field sensor and its system configurationIts basic principle and system configuration have been analyzed and shown. The importance of a linear operation point for the sensor to detect electric field has been analyzed in both the time and the frequency domain. Analysis indicates that the minimum detectable electric field of the sensing system is proportional to the square root of the system bandwidth. The relationship between the maximum linear detectable pulsed electric field of the sensor and its half-wave electric field has been anlyzed. Both the frequency and the time domain test methods of the sensing system have been compared and analyzed.2. Research on the wavelength tuning based operating point control system for integrated optical waveguide electric field sensorThe stability of the sensor operating point is crucial for its performance indicators such as sensitivity, bandwidth and time domain waveform detection. As the drift mechanisms of the sensor operating point is a complex physical process, it is almost impossible to solve this problem only through the improvement of sensor fabrication technology or the change of senor structure. An operating point control system for the sensor has been proposed and realized through software and hardware. Because this is a pure optical control technique, it has any disturbance to the electric field under measurement. Experimental results demonstrate that the precision and the control time of the developed operating point control system can satisfy with the request of the EMP detection in the time domain.3. Research on the three-dimensional (3D) integrated optical waveguide sensing system for measurement of nanosecond EMPThe measuremen of nanosecond electromagnetic pulse (mainly refers to the nuclear electromagnetic pulse) in the time domaint has become one of the key scientific problems need to be resolved in the area of electromagnetic attack and defense. Based on the numerical simulation results using the CST Microwave Studio, two kinds of broadband pulsed electric field sensors have eventually developed. One is the log periodic dipole antenna based 3D nanosecond EMP sensing system with high sensitivity, and the other is the bowtie antenna based 3D nanosecond EMP sensing system with low sensitivity. The time domain test results reveal that the relative errors of the waveform parameters between the detected pulsed electric field and the original EMP are all within 2.5%. The minimum and maximum linear measurable pulsed electric fields of the 3D sensing system are less than 104 V/m and more than 56 kV/m respectively. The frequency response of the developed 3D electric field sensing system is flat from 100 kHz to 1 GHz.4. Research on the 3D integrated optical waveguide sensing system for measurement of intensive microsecond EMPIn high voltage engineering field, the measurement of microsecond EMP which intensity is as high as hundreds, even thousands of kV/m, has great significance to ensure the safety of the power grid. Based on the theory of traveling wave antenna, an integrated optical waveguide sensor with resistively tapered dipole antenna is designed. Then a new type 3D integrated optical waveguide electric field sensor has been developed using three fabricated asymmetric MZI integrated optical waveguide electric field sensors with the tapered antenna has an angle of 54.7° to the straight arm of the MZI. The standard LEMP is used to calibrate the developed 3D sensing system in the time domain, and it is calculated that the maximum detectable electric field of the sensing system can up to 1200 kV/m. At last, it is concluded through theoretical analysis that the noise in the detected EMP waveform is mainly originate from the piezoelectric resonance of LN substrate. Besides, some methods to suppress the noise have also been proposed and discussed.5. Research on the reflective type MZI integrated optical waveguide electric field sensing systemIn order to further reduce the size of the sensor so that it can be used in the narrow space, a reflective type taper antenna array integrated optical waveguide electric field sensor with smaller size has been proposed, designed and fabricated. The time domain experiment results demonstrate that the linear detectable range of the fabricated sensor with 10 pairs of tapered antennas is from 640 V/m to 1.3 kV/m, and the linear detectable range of the sensor with 4 pairs of tapered antennas is from 29.4 kV/m to 58.7 kV/m. Besides, the bandwidth of developed sensing system is tested from 100 kHz to 12 GHz.