Mode Multiplexing Using Principal Modes in Few-Mode Fiber Links With Delayed Feedback

Mode division multiplexing (MDM) in few-mode fibers significantly enhances data rates in fiber links. However, cross-talk due to modal dispersion degrades performance, and this is predominantly compensated through complex MIMO-DSP equalization. "Principal modes" (PMs) of the fiber enable nearly modal dispersion-free communication, though this requires the PMs to be fed back to the transmitter. We propose an effective quantization and feedback method for a PM-based FMF-MDM link that enables equalization-free multiplexing, even with delayed feedback. Simulations reveal that the performance of the proposed approach is close to the ideal PM performance, even with limited quantization and feedback delay.