Structured light routing in CROW-endowed add-drop filters

Abstract

In this paper, we study the propagation of optical vortices (OVs) through the add-drop filter that comprises a coupled resonator optical waveguide (CROW). We develop a fully vectorial theory not based on transfer matrix formalism and apply it to the description of CROWs based on multimode fibers. We study the transmission of higher-order OVs through a CROW-endowed add-drop filter and demonstrate the possibility of transmitting such OVs along the CROW chain. We show that during such transmission OVs may invert their topological charges and determine the condition under which an OV propagates without such charge inversion. We suggest that such a system can be used for the generation of OV frequency combs. We also study group delay time and show that this system may be used as a time delay line for OVs.