Stacked ring resonators for optical vortices

Abstract

In this paper, we study transmission of higher-order modes, optical vortices (OVs) included, through a bus fiber coupled to a vertical stack of ring resonators—stack multi-ring resonator (SMR). We show that transmission curves for OVs feature a characteristic gap-like structure, whose presence we explain as a manifestation of the band structure of an infinite stack of coupled ring resonators. We show a principal possibility to use SMRs as elements of delay lines for fiber optics communications on orbital angular momentum (OAM) states. We emphasize the advantages of such systems as delay lines for communications that use as signal carriers odd and even Laguerre–Gaussian (LG) modes. We also show that SMRs are able to exert super-efficient parametric control over the OAM of the transmitted optical field, as well as to generate OAM beams from odd and even LG modes.