Prism coupling and visualization of surface nanoscale axial photonic structures

Surface nanoscale axial photonics (SNAP) has demonstrated the record subangstrom precise fabrication of miniature optical devices enabling applications in classical and quantum signal processing unfeasible to date. However, SNAP devices formed by subnanometre protrusions of the optical fiber surface lack robustness and simple identification methods. This complicates their controlled alignment and raises concerns about their practical applicability. Here we introduce techniques that enable both direct visualization of nanoscale SNAP features and efficient coupling to fused-silica SNAP microresonators using evanescent-field prism couplers. These advances provide precise control of light-resonator interactions and establish a scalable and robust route towards on-chip integration of SNAP devices, opening opportunities for their critical applications in computing, telecommunications, ultraprecise sensing, and fundamental optical science.