Magnetic-force-induced tunable long-period fibre grating and its application in erbium-doped fibre systems

摘要

Long-period fibre grating (LPFG) is an attractive fibre device that is useful in applications such as gain-flattening filters and fibre-optic sensors, because of low background reflection and easy-to-form large grating period [1]. However, the wavelength-selective loss is generally determined by the fabrication process, e.g., UV laser exposure, and can hardly be tuned later. Therefore the applications of LPFG might be limited to passive filter systems. Several different mechanisms have been proposed to vary the spectral characteristics, which include: pressing, stretching, and heating of the fibres [2,3]. However, the need of machinery to push or pull the fibre may complicate the system and the heating methods are limited in changing the loss amplitude without moving the resonance wavelength. In this study, we present a magnetic-force-induced LPFG (M-LPFG) that can tune the loss amplitude as well as the resonance wavelength.