All-fiber mode converter based on superimposed long period fiber gratings

摘要

In this paper, a novel broadband all-fiber mode converter is proposed and experimentally demonstrated. Through writing a pair of superimposed long period fiber gratings(SLPFGs) in tow-mode fiber(TMF) with a CO_2 laser, the mode converter can realize the conversion from LP_(01) to LP_(11) owing to the phase matching condition. Numerical and experimental results show that the bandwidth of this mode converter is 3 times broader than that of a single grating converter. The converter has low loss, high coupling efficiency, small size and is easy to fabricate, so it can be widely used in mode-division multiplexing.