Photonic Eigenmodes of 2D Cylindrical Cholesteric Liquid Crystal Resonators

Cholesteric liquid crystals (CLCs) are birefringent materials with a helical molecular orientation that enables the selective reflection of circularly polarized light, making them valuable for various optical applications. While extensively studied in planar geometries, their optical properties in cylindrical and droplet-shaped confinements remain less understood. This article numerically investigates photonic eigenmodes in 2D cylindrical CLC resonators with concentric layered and spiral configurations. We demonstrate that the interplay of cylindrical confinement and cholesteric helicity gives rise to distinct optical modes: (i) Bragg-like modes, (ii) central defect modes, and (iii) whispering gallery modes at the boundary or within the bulk. These findings connect the well-known behavior of 1D CLC layers with more complex 2D cylindrical and 3D spherical systems and provide insight into the polarization-dependent mode structure in anisotropic media. The results have implications for designing advanced CLC-based photonic elements such as soft-matter-based lasers and spherical reflectors.