Title :
Compact Long-Period Fiber Gratings With Resonance at Second-Order Diffraction
Author :
Guo, Jing-Chun ; Yu, Yong-Sen ; Zhang, Xu-Lin ; Chen, Chao ; Yang, Rui ; Wang, Chuang ; Yang, Rui-Zhu ; Chen, Qi-Dai ; Sun, Hong-Bo
Author_Institution :
State Key Lab. on Integrated Optoelectron., Jilin Univ., Changchun, China
Abstract :
Compact 5-mm-long 100-μm-period long-period fiber gratings (LPFGs) are fabricated by femtosecond laser direct writing. Nearly symmetrical photomodified grating segments located at the center of a fiber core lead to well-defined transmission spectra. The LPFGs can couple the guided mode to high-order cladding modes of second-order diffraction, resulting in a high refractive index (RI) sensitivity of 5265 nm/RI units in the RI range of 1.433 ~ 1.443 and a low-temperature sensitivity of -15.52 pm/°C from 20°C to 500°C. The latter property is desired for crosstalk-free high-sensitivity RI sensors.
Keywords :
diffraction gratings; fibre optic sensors; laser materials processing; optical fibre cladding; optical fibre fabrication; refractive index measurement; compact long period fiber grating; femtosecond laser direct writing; fiber core; high order cladding modes; refractive index sensitivity; second order diffraction; size 5 mm; symmetrical photomodified grating segment; temperature 20 C to 500 C; well efined transmission spectra; Couplings; Diffraction; Fiber gratings; Fiber lasers; Optical fiber sensors; Sensitivity; Temperature sensors; Femtosecond laser; fiber sensor; long-period fiber gratings (LPFGs); second-order diffraction;
Journal_Title :
Photonics Technology Letters, IEEE
DOI :
10.1109/LPT.2012.2204243
