Microfiber Bragg Grating Hydrogen Sensors

Abstract

In this work, we present a Palladium based hydrogen sensors based on the fabrication of Bragg gratings into optical microfibers. The reflection peak of a grating with a diameter of 3.3 μm can shift by −1.08 nm when exposed to hydrogen with a concentration of 5%, as a result of the evanescent field interaction with the coated Palladium film. The sensitivity is enhanced by 26 times compared with its counterpart in conventional singlemode fiber. The temperature sensitivity is only changed by 27%, and the temperature cross sensitivity is greatly lowered.