Eccentric fiber Bragg gratings via radiation of femtosecond laser pulses

Abstract

Eccentric fiber Bragg gratings (EFGBs) in standard single-mode optical fiber by using point-by-point direct writing technique with 800 nm femtosecond laser. The experimental results show that the transmission spectrum amplitude is coupled by Bragg and cladding mode resonance over a wide spectrum range. Meanwhile, the spectral characteristics of EFBGs were studied by adjusting grating period, grating length, laser power and eccentric distance. The eccentric distance is the most essential parameter in terms of inscribing gratings. It can break up the original structural symmetry of the fiber by changing the offset of grating in the fiber core. This change will bring great opportunities and breakthroughs to the application of EFGBs.