Pico-second vortex output from a large-mode area fiber amplifier

Abstract

High intense optical vortex pulses, exhibiting an orbital angular momentum, have potentially to be applied in various fields, such as optical tweezers, laser micro-fabrication, and laser acceleration. Several researchers have successfully demonstrated ways to produce vortex outputs through mode-conversion in an optical fiber, including a stressed optical fiber as well as a hollow fiber. However, they used mostly a passive fiber as well as a continuous-wave laser. In this paper, we present the production of intense pico-second vortex pulses by selectively coupling a pico-second master laser into LP11 modes in a stressed large mode-area fiber amplifier with an off-axis fiber injection method, for the first time.