A random fiber laser with cylindrical vector beams emission

We demonstrate a random fiber laser with cylindrical vector beams (CVBs) emission. A 9-km-long fiber is applied to form one of the laser mirrors providing random distributed feedback (RDFB). Due to the RDFB provided by the ultralong fiber, mode competitions are well suppressed in the cavity leading to the laser output with modeless behavior. A mode selective coupler (MSC) inserted in the cavity is used to achieve the mode conversion from fundamental mode to cylindrical vector modes. By adjusting the mechanical polarization controllers carefully, both azimuthally and radially polarized beams are achieved with high mode purity. The designed laser retains many advantages of the random lasers, such as low cost and modeless output. The CVBs with modeless behavior may be useful in many practical applications such as biomedical imaging, laser radars and free space communication.