Author:
Jiang Chen,Zhou Kaiming,Sun Bing,Wan Ying,Ma Yuehui,Mou Chengbo,Liu Yunqi
Abstract
We demonstrate the inscription of helical long-period gratings (HLPGs) in a few-mode fiber using femtosecond laser. The first-, second-, and third-order orbital angular momentum (OAM) modes can be directly generated using the HLPGs.