On-demand rapid switching of fiber transverse mode based on a photonic lantern

We propose what we believe to be a new approach to achieve on-demand rapid switching of fiber transverse mode by utilizing a mode-control laser system based on a photonic lantern. The phase conjugate hologram of the transverse mode is loaded onto the liquid crystal spatial light modulator (LC-SLM) to provide an evaluation function for the stochastic parallel gradient descent (SPGD) algorithm of the mode-switching laser system. This system can achieve fundamental mode (FM) and high-order modes (HOMs) with high purity, mode superimposition, and mode switching according to different practical application requirements. The LP₀₁, LP₁₁, and orbital angular momentum (OAM) with a mode purity greater than 90% are obtained, and the superimposed output of the LP₀₁ and LP₁₁ modes is realized. The output can be switched between modes in less than 5 ms. It holds great potential for applications in mode division multiplexing (MDM), industrial materials processing, and high-power fiber lasers.