Study of high temperature stable fiber Bragg gratings fabricated in H 2 loaded and unloaded SMF-28 fiber

Abstract

High reflectivity fiber Bragg gratings are written with ultrafast infrared radiation in H 2 loaded SMF-28 fiber that retain in excess of 60 percent of their index change at 1000 °C using writing intensities below the damage threshold of the fiber. The reflectivity after annealing (>-15 dB transmission loss at the Bragg resonance) and index modulation ( i × 10 -3 ) in these devices is significantly higher than what can be achieved with UV devices such as Type II, Type IIA and chemical composition gratings. In this study the stability of these devices is compared to that of gratings fabricated in unloaded SMF-28 fiber.