Scalable All-Optical Fibre-Mode Data Transmission with Profiles-Preserved Decoding

Optical fibres are the primary medium for optical signal transmission, and their guided modes provide a high-dimensional basis for modal-domain information encoding. However, conventional demultiplexing approaches typically convert fibre modes into fundamental Gaussian modes and require repeated mode conversions, while existing profiles-preserved methods are generally restricted to fewer than three modes. High-quality fibre-mode data transmission therefore requires a scalable all-optical decoder capable of separating strongly overlapping modal channels while preserving their intrinsic spatial profiles. Here, we establish a scalable profiles-preserved all-optical decoding method for high-dimensional fibre-mode data transmission. By introducing a microlens-array-assisted decoding architecture with channel-dependent spherical phase compensation, the proposed method accommodates mode-dependent effective focal-length variations, enabling scalable modal-channel separation while preserving high-quality modal profiles at the output plane. Experimentally, the optical decoder resolved fields containing eight fibre modes, achieving a mode fidelity exceeding 0.72, a worst-channel crosstalk of $-5.57~\mathrm{dB}$ and a mean non-target crosstalk of $-21.34~\mathrm{dB}$, while reconstructing the relative modal weights with an error below 0.1. Semantic transmission experiments using digits and Chinese characters further demonstrated effective recovery of the encoded information from the decoded modal signals. We expect this work to provide a scalable route towards high-dimensional all-optical fibre-mode data transmission.