All-Fiber Orbital Angular Momentum Laser Generated with Titled Fiber Bragg Grating Pair written in Few-Mode Ring-Core Fiber

An all-fiber method of orbital angular momentum (OAM) beams laser generated is proposed. The laser cavity is formed by a pair of few-mode fiber based titled fiber Bragg gratings, which convert pump light to OAM beams. The OAM beams with ℓ = ±1 in vertical polarization were characterized experimentally. Besides, the lasing stability and efficiency are demonstrated. This stable and compactable all-in-fiber OAM laser can be an effective application in optical communication, sensing and quantum information processing.