UBC Theses and Dissertations
Infrared integrated optics pockels cell high-voltage sensors Mirabedini, Ali Reza
This thesis presents a study of the theory of operation, fabrication, and characterization of the infrared Integrated Optics Pockels Cell (IOPC) as a high-voltage sensor. The IOPC is primarily a polarization controlling device which employs the linear electro-optic effect (Pockels effect) of lithium niobate to measure an electric field. A complete IOPC-based system consists of an infrared laser, polarization preserving fibers to deliver and receive polarized light to and from the sensor-head, a sensor-head to be placed in the high-voltage environment, and photodetectors to convert optical signals to electrical ones. The sensor head is basically formed by a z-propagating titanium diffused channel waveguide in a y-cut lithium niobate substrate. The theory of operation of the IOPC is explained and, as the characteristic equation of the sensor, a normalized optical-intensity-out/electric-field-in transfer function is derived. A mathematical description of the Ti:LiNbC>3 channel waveguide as a function of the fabrication parameters is provided; then, the associated optical field distribution, using numerical methods, is calculated. Also, an approximate analytical expression for the intrinsic difference between the propagation constants of the TE- and TM-like modes in a z-propagating Ti:LiNb03 channel waveguide is derived. To justify our method, the derived expression is applied to a simple waveguide case for which analytical solutions are possible. The experimental part of work consists of the fabrication of the sensor-head and construction of a completely integrated sensor. The fabrication procedures and integration steps taken to realize a fully connectorized IOPC sensor are explained in detail. In order that IOPC should be considered as a plausible alternative to conventional potential transformers for high-voltage measurements, its performance should be at least as good as the current technology. In this regard, various tests were conducted on the fabricated IOPCs to measure device characteristics and evaluate their performance under various conditions. It is concluded that the sensor is capable of meeting the standards suggested for AC voltage metering and high-voltage switching-impulse monitoring.
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