High power vortex random lasing in an all-fiber structure

A vortex beam has broad development prospects in free space optical communication, optical tweezers, super -resolution imaging due to its unique helical phase distribution and orbital angular momentum. Traditional free-space based methods of generating vortex beam involve complex bulky structures and it is extremely difficult to acquire high power output of vortex beam. In this paper, a mode converter based on a long period fiber grating (LPFG) is used to excite the vortex beam. By further combining the LPFG and the structure of random fiber laser (RFL), we demonstrate an all-fiber structure vortex RFL. Our vortex RFL presents the typical intensity distribution of doughnut shape of vortex beam. The maximum output power of the vortex RFL reaches 3.77 W benefiting from the all-fiber structure, which also improves the integration of the laser system markedly. In addition, we measure the output properties of the vortex RFL, which show excellent temporal stability, modeless output and low relative intensity fluctuation. This work may not only offer a potential scheme for producing high power vortex beams, but also promote the application prospect in free space optical commu-nication, lidar, biological imaging and remote sensing.

Automated summary

In this paper, a fiber-based vortex random fiber laser (RFL) with a maximum output power of 3.77 W is demonstrated using a mode converter based on a long period fiber grating (LPFG) and the structure of random fiber laser (RFL). The vortex RFL shows excellent properties including doughnut-shaped intensity distribution, temporal stability, modeless output, and low relative intensity fluctuation. This work not only provides a potential scheme for high power vortex beam generation, but also promotes the application prospect in various fields.