Robust Super-Resolution Image Transmission Based on a Ring Core Fiber with Orbital Angular Momentum

Single-fiber imaging technology offers unique insights for research and inspection in difficult-to-reach and narrow spaces. In particular, ultra-compact multimode fiber (MMF) imaging, has received increasing interest over the past decade. However, MMF imaging will be seriously distorted when subjected to dynamic perturbations due to time-varying mode coupling, and the imaging of space objects via Gaussian beam will be relatively degraded at the edge due to insufficient contrast. Here, a robust super-resolution image transmission method based on a ring core fiber (RCF) with orbital angular momentum (OAM) is proposed and experimentally demonstrated. The OAM modes propagating in the RCF form a series of weakly coupled mode groups, making the imaging system robust to external perturbations. In addition, a spiral phase plate is used as a vortex filter to produce OAM for edge enhancement, thus improving the image resolution. Furthermore, a few-shot U-Transformer neural network is proposed to enhance the resilience of the developed RCF-OAM imaging system against environmental perturbations. Finally, the developed RCF-OAM imaging system achieves biological image transmission, demonstrating the practicality of the scheme. This pioneering RCF OAM image transmission system may have broad applications, potentially revolutionizing fields such as biological imaging and industrial non-destructive testing.