A hydrogen curing effect on surface plasmon resonance fiber optic hydrogen sensors using an annealed Au/Ta2O5/Pd multi-layers film

In this paper, a response time of the surface plasmon resonance fiber optic hydrogen sensor has successfully improved with keeping sensor sensitivity high by means of hydrogen curing (immersing) process of annealed Au / Ta2O5 / Pd multi-layers film. The hydrogen curing effect on the response time and sensitivity has been experimentally revealed by changing the annealing temperatures of 400, 600, 800 degrees C and through observing the optical loss change in the H-2 curing process. When the 25-nm Au / 60-nm Ta2O5 / 10-nm Pd multi-layers film annealed at 600 degrees C is cured with 4% H-2 / N-2 mixture, it is found that a lot of nano-sized cracks were produced on the Pd surface. After H-2 curing process, the response time is improved to be 8 s, which is two times faster than previous reported one in the case of the 25-nm Au / 60-nm Ta2O5 / 3-nm Pd multi-layers film with keeping the sensor sensitivity of 0.27 dB for 4% hydrogen adding. Discussions most likely responsible for this effect are given by introducing the alpha-beta transition Pd structure in the H-2 curing process. (C)2014 Optical Society of America