Photonic modes in anisotropic topological soft matterMur, Urban (Avtor) Ravnik, Miha (Mentor) lightnematic liquid crystalnumerical simulationscontroltopologyphotonic crystallight beameigenmodepixelThis thesis numerically explores ideas for the realisation of novel photonic modes using anisotropic topological soft matter, with the control over material birefringence being the central underlying concept. The work is focused on analyzing the interplay between light and material, especially by use of topological defects and concepts of photonic topological insulators. The main methodological approach is Finite Difference Frequency Domain (FDFD) method, which is specifically developed to calculate eigenstates in the anisotropic optical resonators by adapting and improving upon existing FDFD approaches and can account for arbitrary spatially varying optical axis of uniaxial birefringent material. First optical system explores eigenmodes of different liquid crystal structures, like nematic droplets, defects and layers, embedded in Fabry-Pérot resonator. Shapes of the intensity profiles of the emerging modes are found to depend on the shape of the cavity, determined by its refractive index profile, while the polarization profiles show strong dependence on the spatially varying nematic director field. Under second research direction, we explore the possibilities for deflection and control of the light beam intensity profiles by using stacks of liquid crystal cells. Combinations of individually controlled building blocks show the ability to control the light beam continuously. The proposed device can operate in a broader wavelength spectrum and is capable of splitting the beam and controlling each part individually. A third system looking at the effects of pixelization on photonic crystal band gaps is studied on the case of cylindrical pillars in a square lattice. We show that already simple approximations of the circular pillar cross sections act similarly to the original structure with only a small mismatch in the photonic band structure. The demonstrated concept is used to construct a perturbed pixelated photonic crystal based on the Kagome lattice, which supports the existence of unidirectional states at the domain boundaries. Further, unidirectional states are also shown in a perturbed pixelated Kagome lattice photonic crystal based on liquid crystals, which offer a possibility of constructing a topological photonic crystal with reconfigurable boundaries. In the fourth line of research, characteristics of negative birefringence nematic liquid crystal reordering in the vicinity of umbilical defects in the presence of external electric field are examined. More generally, the work explores new concepts for using soft materials for real-time shaping and control of the light at the microscopic level.20212021-11-06 08:15:03Doktorsko delo/naloga132920VisID: 122914COBISS_ID: 85091075sl