An All-Fiber Reflective Hydrogen Sensor Based on a Photonic Crystal Fiber In-Line Interferometer

A new method based on introducing a photonic crystal fiber (PCF) in-line interferometer for hydrogen sensing is demonstrated. One end-face of the PCF and part of the outer-face of the fiber are plated with a thin palladium film by magnetron sputtering, while the other end is connected to the optical path. Therefore, a set of reflection-type all-fiber hydrogen sensor system is accomplished. Hydrogen concentration from 0% to 5% was detected in the experiment and the related interferometric resonant wavelength-shift was recorded. The maximum wavelength shift is over 1.2 nm. The whole system has an all-fiber optical path without any bulk-optic components, and this design obtains a high level of integration, a high stability, and low production costs.

I. Introduction

As One kind of industrial raw materials, hydrogen plays an indispensable role in many different fields such as petrochemical, electronics industry, metallurgical industry, food processing, new energy etc. However, hydrogen molecule can easily leak since it is the lightest and smallest molecule. In air, the concentration of hydrogen exceeding 4% will cause an explosion under the emergence of even a spark. Therefore, in the process of transportation, storage and use, real-time monitoring of the environmental hydrogen concentration is a very necessary security work.