Generation of highly pure lower-order Laguerre–Gaussian radial beams using an all-fiber multimode interference method

We show that the output beam exiting from the end facet of a single-mode–multimode–few-mode device can be designed to be a highly pure LG00 or LG01 mode. Our investigation provides a method to generate LG beams in free space using a low-cost, all-fiber solution that also shows potential for an integrated device.