Sapphire-fiber thermometer ranging from 20 to 1800 degrees C

A novel, to our knowledge, sapphire-fiber thermometer ranging from 20 degre es to 1800 degrees C is presented that combines the radiance detection and the fluorescent lifetime detection schemes into one system. The thermal pro be is a sapphire fiber grown from the laser-heated pedestal growth method. Its end part is doped with Cr3+ ion and coated with some radiance material to constitute a minifiber cavity. The sapphire fiber is coupled with a Y-sh aped silica fiber bundle for signal transmission. Radiance and fluorescence signal processing schemes are also set up within one thermometer system. i i sandwich two-band p-i-n detector is used that may respond to both the rad iation and the fluorescence. Preliminary experimental results show that the thermometer is suitable for practical application with potential long-term stability and a high-temperature resolution. (C) 1999 Optical Society of A merica.