Nano-thick SiO2 channel for subwavelength plasmonic orbital angular momentum mode transmission

Orbital angular momentum (OAM) waveguides are critical for multi-channel photonic-on-chip applications.However, current large-mode-area waveguides pose a challenge for OAM device miniaturization.Here, a novel hybrid plasmonic waveguide is theoretically proposed to decrease the OAM mode area by two orders of magnitude.Benefiting from the Ag-As 2 S 3 -SiO 2 -As 2 S 3 -Ag five-layer cylindrical structure, the guided OAM mode realizes a larger figure of merit of 88.Based on this waveguide, an OAM coupler with a record-breaking small footprint (0.68 m 5.7 m) is designed.The proposed waveguide enables subwavelength OAM light transmission, which provides a key building block for high-density OAM photonics circuits.