Flow of light in metamaterials based on nematic fluidsPusovnik, Anja (Avtor) Ravnik, Miha (Mentor) metamaterialshyperbolic metamaterialscolloidstunabilitynematic liquid crystalsheliconical liquid crystalsamorphous structureThis Thesis explores the flow of light in metamaterials based on nematic fluids. We study light propagation through optical metamaterials, capable of controlled and novel optical performance, specifically focusing on the role of birefringent media in materials that include nematic liquid crystals. Methodologically, the main approach was finite-difference time-domain method, adapted for the simulations of birefringent, frequency-dispersive and absorptive media. Firstly, we consider light propagation in homogeneous materials with eigenvalues of permittivity tensor of opposite sign -- hyperbolic metamaterials. The refraction of light into a material with fixed optical axis shows a strong dependence of the Poynting vector propagation, on the optical axis direction, with a possibility of positive or negative refraction. The flow of light is further developed in the analysis of the light propagation through defect-like optical axis profiles of hyperbolic metamaterial, notably demonstrating attractor and deflector type of propagation, as well as with the possibility of beam guiding with e.g. sinusoidal optical axis profiles. Secondly, we study metamaterials based on specific colloidal structures, composed of individual metallic split-ring (SRR) particles, embedded in nematic liquid crystals. We study the transmissivity for an individual SRR particle, for 2D and 3D crystals, and demonstrate a resonant-like response in optical transmissivity of the material, which depends on particle geometry, size and material composition, on coupling between the individual particles, and also on the nematic field, surrounding the particles, which opens a possibility for tuning of the optical response of the structure with external fields. And thirdly, we explore the flow of light in selected birefringent structures: heliconics, transient quench structures of nematics and BPIII. For heliconical liquid crystals, we show the relation between the band gap position and the structural properties of heliconics, specifically the periodicity (pitch) and helical tilt angle. The analysis of spatial dependence of transmitted light in amorphous (non-periodic) structures of liquid crystal disclination lines, distinctly in thermally quenched nematics from isotropic to nematic phase and in the BPIII phase, reveals the light response from subwavelength variations of birefringence. More generally, the work is a contribution to the fields of metamaterial photonics and soft birefringent materials by designing novel birefringent (meta)materials capable of controllable and tunable photonic properties importantly originating from birefringent components.20202020-03-08 08:15:06Doktorsko delo/naloga114769VisID: 106377COBISS_ID: 3412324sl