Localization of Light in Multi‐Helical Arrays of Discrete Coupled Waveguides

Abstract Localization of light in disordered or periodically structured dielectric media has been studied for many years. A recent example is coreless (i.e., defect‐free) photonic crystal fiber (PCF), which observed to confine when drawn chiral form from a spinning preform. Although heuristic arguments based on radially‐dependent bandgap have advanced, the underlying mechanism not fully resolved. Here, novel analytical model twisted PCF presented, arrays coupled single‐mode step‐index sub‐cores chirality causes effective axial refractive index cores rise quadratically with radius. It produces results excellent agreement numerical solutions Maxwell's equations, while offering orders magnitude reductions computational time. As result it possible treat structures very large numbers sub‐cores, clarify confinement mechanism, and establish that exponentially localized helical Bloch modes (HBMs) do indeed form. an example, localization hexagonal honeycomb lattices studied, shown every case whole families guided HBMs exist. The open new chapter 2D light.