Optical properties of metamaterial split ring nematic colloids

The fabrication of 3D bulk metamaterials, optical materials with sub-wavelength building blocks, is an open challenge, along with the tuning of their optical properties, such as transmissivity or exit polarization where a possible approach is to embed liquid crystalline materials into metamaterials and use their tunable birefringence. In this work, we explore using numerical modelling the photonic properties of a composite of split ring resonator colloidal particles, dispersed in nematic liquid crystal, which was optimised to enable self-assembly fully. Specifically, using generalised FDTD simulations for light propagation in birefringent profiles, we demonstrate the photonic response of single particles, 2D and 3D colloidal crystals. The material transmittance is shown to exhibit clear resonant behaviour with the resonances tunable with the birefringence in the order of ~5%. Electric and magnetic field modes emergent on the particles are shown, as affected by the surrounding nematic birefringence, both the in the slit region of the split ring resonator (SRR) particles as well as around the particles. Observed photonic response is further explained by introducing basic equivalent LC circuits. Finally, this work is aimed at developing soft and fluid metamaterials, which exhibit optical anisotropy in the photonic response as a potent mechanism for controlling the flow of light at wavelength and even sub-wavelength scales.