| Summary: | 博士 === 國立交通大學 === 電子工程系 === 88 === In the dissertation, the fundamental and various configurations for electro-optic probing are carefully introduced first. Using this technique, the waveform measurements up to 1 GHz signals were successfully demonstrated. Then, an electro-optic probing tip made of a LiTaO3 crystal to do a tangentially two-dimensional electric-field vector measurement is presented. A new electro-optic modulation technique and a conventional one are combined to resolve the two electric-field components. Instead of conventional compressed/stretched deformation of the index ellipsoid, the new modulation effect on the optical probing beam is caused by the principal axis rotation of the index ellipsoid, which is also proportional to the applied electric-field strength. Since there is no free charge involved in the axis rotation, the axis-rotation modulation can be as fast as the conventional type. The principles are derived and an experimental system is constructed to perform the measurement of two-dimensional electric-field vectors on a test pattern. The results are in good agreement with those obtained by the commercial "Ansoft Maxwell 3-D Field Simulator'''' software for electromagnetic simulation. The sensitivities for two tangential electric-field component are 76 mV/cm/(Hz)1/2 and 0.8 V/cm/(Hz)1/2. The root-mean-square error of electric-field direction measurement is 1.5°.
In order to perform three-dimensional electric-field vector measurement, another new technique of using three laser beams with different propagation paths in an electro-optic crystal was proposed. The retardation of each beam is differently affected by each one of three electric-field components. Therefore, once individual effect of three electric-field components on each beam can be characterized, for given retardation of three beams, all components of three-dimensional electric-field vector can be resolved. Two kinds of similar crystals with the simple electro-optic tensor form, KH2PO4 (KDP) and Bi12SiO20 (BSO), were analyzed to find which one is more suitable for this technique. The result showed that BSO was the better one. An experimental system using a probe tip made of BSO crystal was constructed. Three sets of data from simulation results obtained by the same software mentioned above were used for calibration purpose. After the calibration process, the measurement results were in good agreement with all the simulation results. In this experimental system, a sensitivity of 0.6 V/cm/(Hz)1/2 was achieved.
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