Robust orbital-angular-momentum-encoded information transmission in multimode fiber against slowly varying stochastic dynamics

Large-core multimode fibers (MMFs) hold significant potential for long-distance transmission of high-capacity spatial information, such as orbital-angular-momentum (OAM) encoded data, between two arbitrarily separated senders and receivers. However, the originally well-defined wavefront may deteriorate into speckles during propagation, creating an urgent need for efficient information extraction from MMF-generated speckles. In addition, in long-distance MMF systems, the wavelength drift from laser sources and the inevitable environmental perturbations are prone to inducing dynamic fluctuations in the speckle field, which disable conventional static scattering-based information extraction approaches. Here, we directly address the challenge of the slowly varying dynamics inherent to information transmission systems with long-distance MMF. By investigating the decorrelation characteristics of OAM-dependent MMF speckles, we propose a time-division demultiplexing strategy to mitigate the effect of the slowly varying stochastic MMF speckles. Notably, this approach enables flexible tradeoffs between data transmission efficiency and quality under lower calibration overhead, which can be dynamically adjusted according to the actual dynamic properties of the MMF system. This work offers a promising solution for OAM-encoded information transmission under slowly varying stochastic dynamics in practical scenarios.