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[15a-2F-1] Response characteristics for SPR hydrogen sensor based on hetero-core structured optical fiber with Au/Ta2O5/Pd/Pt multi-layers
Keywords:optical fiber,hydrogen sensor,platinum
Most of the fiber-optic hydrogen sensors using palladium (Pd) or alloy content Pd have been reported due to its high sensitivity and selectivity for hydrogen. However, Pd would bring about the deterioration which makes reproducibility of the response characteristic worse because of phase transition occurs in the course of the adsorption and emission of hydrogen. As a conventional study, a surface plasmon resonance (SPR) hydrogen sensor using optical fiber based on hetero-core structured with Au/Ta2O5/Pd multi-layers have been developed. In this paper, forming platinum (Pt) to the conventional SPR hydrogen sensor based on hetero-core optical fiber structures, we intend to suppress the deterioration to sensor’s reproducibility of response characteristic. Experiment was performed with an LED operated at 850nm wavelength and PD owing to confirm the change of the response characteristics on the time-dependent change. Three sensors were prepared for this experiment with different kinds of layer film thicknesses: three had fixed thicknesses of 25nm Au/60nm Ta2O5/5nm Pd with different thicknesses of the Pt outermost layers for nothing (0nm), 1nm and 2nm. As a result, differences of the optical loss changes from 1st day to 5th day are indicated to be 0.044dB for 5nm Pd film, 0.016dB for 5nm Pd/1nm Pt and 0.025dB for 5nm Pd/2nm Pt. Therefore, delay of response times (how long time-lag exists) from 1st day to 5th day were exhibited to be 10s for 5nm Pd, 1s for 1nm Pt and 2s 2nm Pt. These results suggest that forming Pt film to conventional SPR hydrogen sensor suppresses the deterioration which would affect sensor’s reproducibility of response characteristic.