Abstract
Chiral structures exhibit strong interactions with circularly polarized light, and have been demonstrated to show many polarization dependent properties, such as circular dichroism. In this study, we use a complete and incomplete dielectric helix array as a model system to examine the interactions of circularly polarized light with helical structures. A dielectric helix array produces the circular polarization band gaps having not only the same handedness with the structure but also the opposite handedness. The gap with the opposite handedness results from additional chiral motifs induced by the adjacent helices. Dual polarization band gaps can thus be tailored by varying the geometrical parameters, and circular-polarization dependent properties can be manipulated for optoelectronic devices and applications. Hyperbolic metamaterial (HMM) has attracted considerable attention owing to several exotic optical properties. One of these is the enhanced spontaneous emission, resulting from the hyperbolic dispersion of HMM. However, the out-coupling of light from HMMs is difficult due to the evanescent character of the high-k modes at the surface. In this study, the optical properties of nanowire HMMs with the enhanced structure are characterized. The results show the loss in the system is reduced, and the high-k modes of HMM is coupled out by virtue of the enhanced structure. The radiative enhancement can reach the value of 7.2 in the infrared region. The resonances inside the nanowire HMM are also analyzed to examine the mechanism of the enhancement of light. The analysis results are important toward engineering highly-efficient photonic devices based on HMMs.