Generation of multiwavelength cylindrical vector beams from a random fiber laser assisted with nonlinear amplifying loop mirror

In past decades, vector mode random fiber laser (RFL) has attracted much exploration and rapid development. In this work, we proposed and demonstrated a novel multiwavelength RFL that produces cylindrical vector beams (CVBs). The gain profile is manipulated by a homemade Sagnac loop filter assisted with the nonlinear amplifying loop mirror (NALM) mechanism to improve multi-wavelength oscillation capability. The CVBs are generated with the help of long-period fiber grating and the wavelength switchablity CVBs random fiber laser is obtained. The wideband spectrum multiwavelength CVBs with the maximum channel number of seventeen are realized with NALM. This currently holds the record for the highest number of wavelength channels of vector mode random lasers which holds great promise for free-space optical communication. Coherent-tunable low-coherence high-order modes and cylindrical vector mode random lasers utilizing wavelength tailoring have been realized with high mode purity. The proposed CVBs with modeless behavior have potential applications prospects in optical signal multiplexing, space optical communication, and speckle-free laser active imaging.