Mode Conversion Using a Digital Micromirror Device and Optimized Phase Masks

Precise control of propagation modes in optical fibers is essential for optimizing performance in high-speed communication systems based on mode division multiplexing (MDM). In this work, we propose an approach for modal conversion in few-mode fiber (FMF) communication systems using a digital micromirror device (DMD) and phase masks optimized with a simulated annealing algorithm. Although the DMD is an amplitude spatial light modulator, here it is used to convert the laser beam between different modes using the designed phase masks and the Lee holograms technique. We experimentally demonstrate the effectiveness of this approach for converting light to specific modes propagating in free space, which can later be coupled into an FMF.