Monolithically integrated 3D polymer Möbius ring resonator–waveguide system

A monolithically integrated 3D polymer Möbius ring resonator-waveguide system is designed and fabricated using two-photon polymerization for operation at telecommunication wavelengths. The integrated structure ensures precise coupling and stable optical confinement. Distinct polarization-dependent transmission spectra were observed, revealing continuous polarization evolution along the Möbius path, which was further verified by FDTD simulation. Compared with a conventional microtoroid of identical radius (44 µm) and material, the Möbius resonator exhibits a free spectral range (FSR) that is reduced by half, consistent with its doubled optical round-trip length. These results demonstrate that the Möbius topology fundamentally modifies the behavior of both polarizations and the resonance periodicity, offering a compact platform for topology-induced photonic control and spectral engineering in integrated polymer microresonators.