Efficient dynamic free-space-to-fiber coupling of cylindrical vector beams via twisted moiré meta-devices

Efficient free-space-to-fiber coupling of cylindrical vector beams (CVBs) is critical for long-haul communication and network node access with mode-division multiplexing. Current direct coupling suffers from mode-order-dependent divergence yielding mode-field mismatch and inadequate beam ring-radius adjustment causing interface misalignment, constraining coupling efficiency, crosstalk suppression, and dynamic adaptability. Here, we introduce a twisted moiré transformation solution that develops ring radius-adjustable perfect CVBs using paired meta-devices for efficient dynamic free-space-to-fiber coupling. Incorporating the axicon-modulated Fourier transformation with in-plane twisted moiré operation, this approach not only suppresses divergent beam expansion in multiplexed CVBs, but also enables rotation-controlled continuous tuning of beam ring radii (0.0955−0.7430 mm) for optimal fiber-core dimension matching, achieving ~80.7% higher coupling efficiency and ~2.75 dB greater crosstalk suppression versus conventional direct coupling. Demonstrated with 14.1 Tbit s−1 quadrature phase shift keying (QPSK) signal transmission over 282-channel multi-dimensional multiplexing, our findings represent a substantial advance toward practical CVB-based communications and transformative integrated free-space-to-fiber optical networks. Efficient free-space-to-fiber coupling of cylindrical vector beams (CVBs) is crucial for high-capacity optical communications, yet remains constrained by low coupling efficiency and poor dynamic adaptability in conventional methods. The authors address this issue by introducing a twisted moiré transformation approach that develops ring radius adjustable perfect CVBs using paired meta-devices