Thermal Durability of Sapphire Optical Waveguides Processed Into High Temperature Ceramic Composites

摘要

Comprehensive research work was performed between the period beginning April 92 to June 95, to fabricate sapphire optical waveguides, embed them in high temperature ceramic composites and to develop a sensing technique. Commercially available plastic or silica optical fibers cannot be used at high temperatures (1000 C) since they either degrade or soften much below these temperatures. To characterize high temperature ceramics, a new kind of optical fiber and sensing technique appropriate for high temperatures need to be developed. Therefore, it was the objective of this research effort to develop an optical waveguide and sensing technique for high temperatures and embed the waveguide in ceramic composites for high temperature sensor applications. Specifically, the main objectives were: (1) To design and fabricate sapphire optical waveguides; (2) To develop a sensing technique for multimode sapphire optical fibers; (3) To embed sapphire optical fibers in aluminum oxide (Al203) matrix; and (4) To study the thermal fatigue response of the processed alumina samples with embedded sapphire optical fibers. This report discusses the results obtained in each of these areas and the conclusions that can be drawn. Significant novel concepts were proposed and considerable success obtained in this study.