Design of high-sensitivity metal-coated LPFG sensor based on material dispersion

Abstract:

A high-sensitivity metal-coated long-period fiber grating (LPFG) sensor based on material dispersion is designed. Based on the coupled mode theory, the influence of the material dispersion on the dual-peak characteristics of the metal-coated LPFG is studied. After considering the material dispersion, the jumping region of the dual-resonant-wavelength shifts toward the thinner film thickness, and the sensitivity of the dual-peak metal-coated LPFG sensor to liquid refractive index (RI) can be obtained to supply accurate parameter combinations. Experimentally, two kinds of silver-coated LPFGs with different film thicknesses and grating periods are fabricated to monitor the salt solution, and the sensitivities of these two sensors are compared. The experimental results are consistent with the theoretical analyses. This work has been supported by the National Natural Science Foundation of China (No.60777035), the Scientific Research Key Project Fund (No. 208040), the Innovation Program of Shanghai Municipal Education Commission (No.11ZZ131), and the Shanghai Leading Academic Discipline Project (No.S30502).