Gauge-flux-controlled orbital angular momentum mode conversion in silicon waveguides

We propose a method to convert fundamental modes into orbital angular momentum (OAM) modes through chiral dynamics induced by gauge fluxes in silicon waveguides. By integrating a trench into a few-mode waveguide, we induce the rotation of TE₁₀ and TE₀₁ modes, naturally generating the gauge flux for the synthesized OAM modes. By precisely controlling the gauge flux, we achieve chiral dynamics that optimize the conversion efficiency of OAM modes at specific propagation distances, addressing challenges posed by mode degeneracy. Additionally, we demonstrate an on-chip OAM mode (de)multiplexer based on flux-controlled mode conversion. Our findings offer new, to the best of our knowledge, strategies for creating artificial gauge fluxes in straight waveguides and open up possibilities for manipulating OAM modes on photonic chips.