Sapphire Fiber Bragg Gratings with Improved Spectral Properties for High-temperature Measurements

We propose the polishing process to obtain a smooth and flat sapphire fiber end face. And the end reflection of the sapphire fiber can be measured by employing the tunable laser and power meter. We study several methods to measure the spectra of sapphire fiber Bragg gratings (SFBGs). The signal to noise ratio (SNR) of sapphire fiber Bragg gratings decreases with increasing propagation distance due to the uneven diameter of sapphire fiber. The high-temperature response of these SFBGs was tested and the experimental results showed the SNRs of SFBGs decreased at a high temperature of 1785 degrees C. Hence, such SFBGs could be developed for promising high temperature sensors in metallurgical, chemical, and aviation industries.