Open AccessCompact eccentric long period grating with improved sensitivity in low refractive index region
Author(s) -
Fangcheng Shen,
Kaiming Zhou,
Neil T. Gordon,
Lin Zhang,
Xuewen Shu
Publication year - 2017
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.25.015729
Subject(s) - refractive index , optics , grating , materials science , cladding (metalworking) , femtosecond , normalized frequency (unit) , step index profile , laser , optoelectronics , graded index fiber , optical fiber , physics , fiber optic sensor , phase locked loop , frequency synthesizer , phase noise , metallurgy
We demonstrate a compact eccentric long period grating with enhanced sensitivity in low refractive index region. With a period designed at 15 µm for coupling light to high order cladding modes, the grating is more sensitive to surrounding refractive index in low refractive index region. The intrinsically low coupling coefficients for those high order cladding modes are significantly improved with the eccentric localized inscription induced by the femtosecond laser. The fabricated grating is compact with a length of 4.05 mm, and exhibits an average sensitivity of ~505 nm/RIU in low refractive index region (1.3328-1.3544). The proposed principle can also work in other refractive index region with a proper choice of the resonant cladding modes.