Open AccessSimulation and analysis of sensing modes of in-fiber interferometer
Author(s) -
Lijun Li,
Qiang Ma,
Xingzhen Bai,
Shunshun Gong,
Wenxian Li,
Xin Guo,
Yilin Liu,
Lin Xu,
Qian Liu
Publication year - 2017
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
ISSN - 1000-3290
DOI - 10.7498/aps.66.220202
Subject(s) - cladding (metalworking) , optics , cladding mode , materials science , superposition principle , refractive index , optical fiber , step index profile , interference (communication) , interferometry , graded index fiber , normalized frequency (unit) , core (optical fiber) , single mode optical fiber , fiber optic sensor , physics , polarization maintaining optical fiber , telecommunications , computer science , channel (broadcasting) , phase locked loop , quantum mechanics , frequency synthesizer , phase noise , metallurgy
The cladding mode of the in-fiber interference sensor relates to the externally sensing physical quantity, so the investigation of the cladding mode is very important for designing and improving the sensing performance of the sensor. By using the finite difference beam propagation method, the interference spectra of the sensors with different lengths and different core-to-core diameter ratios are simulated. Its spatial frequency spectrum is obtained through Fourier transform. The effective refractive index of the dominant cladding mode can be obtained through analyzing its spatial frequency spectrum. Its corresponding cladding mode order can be determined through substituting the values of the effective refractive index into the dispersion equation of sensing optical fiber. The simulation results show that the number and the order of the cladding modes both increase with sensing part fiber length increasing. The interference spectrum becomes dense according to the superposition of multi order cladding mode interferences. Its free spectral space of the sensor output interference spectrum becomes small. With the variations of the input fiber and sensing fiber core-to-core diameter ratio, the power distributions among the modes change obviously. The increase of core-to-core diameter ratio can increase the number and order of the cladding modes.