Design of Palladium-Coated Long-Period Fiber Grating for Hydrogen Sensing

作者：Basumallick Nandini; Biswas Palas; Carter Richard Mark; Maier Robert R J; Bandyopadhyay Sankhyabrata; Dasgupta Kamal; Bandyopadhyay Somnath

来源：Journal of Lightwave Technology, 2016, 34(21): 4912-4919.

DOI：10.1109/JLT.2016.2604481

• Hydrogen detection
• long period fiber gratings
• mode transition
• palladium coatings
• turn-around-point grating

We present a detailed numerical analysis that describes the influence of palladium (Pd) layer thickness on the spectral characteristics of long-period fiber gratings (LPFGs) and their response to the uptake of hydrogen. The investigation is carried out with a view of determining an optimal layer thickness to design high-sensitivity LPFG-based hydrogen sensors. Coupled differential equations for a four-layerwaveguide structure have been solved using a matrix method considering a layer of Pd with finite thickness on the cladding. Response of higher order cladding modes of the Pd-coated LPFG at turn-around-point and also at mode transition could be computed. It has been shown that if properly designed, the resonant wavelength of a desired mode may shift by about 20 nm for 1% uptake of hydrogen. There is good match between simulations and experiments for LPFGs with coupling to higher order cladding modes

• 出版日期2016-11-1