Guided-mode waves structure of electric and magnetic dipole resonances in a metamaterial slab.

The electric dipole (ED) and magnetic dipole (MD) resonances in a slab of dielectric nanostructures induced by oblique light incidence were analyzed in terms of guided-mode wave theory for transverse electric (TE) and transverse magnetic (TM) polarization. Owing to the symmetry breaking in TE and TM polarizations at oblique incidences of light, the resonance modes produced different features, which were analyzed with comprehensive studies of energy fluxes associated with the resonance modes. The MD resonances are excited by the guided-mode wave with an energy flux in the opposite direction in the incident plane for TM polarization and excited by two guided-mode waves with energy fluxes orthogonal to the incident plane for TE polarized light. Meanwhile, the ED resonances are excited by the guided-mode waves with energy fluxes in both directions, incident plane, and out of the incident plane for both TE and TM polarizations. The proposed analyses provide clear explanations of the stability or vanishing of resonance modes, with variations in the inter-distance between nanostructures near the Rayleigh anomaly condition, which were verified by the experimental measurements performed with 2D arrays of Si nanostructures for various incident angles with TE and TM polarizations.

Switching of liquid-crystal devices between reflective and transmissive modes using long-pitch cholesteric liquid crystals.

We propose liquid-crystal (LC) devices capable of switching between reflective and transmissive modes using the scattering and transparent states of long-pitch cholesteric LCs (CLCs). Two different device configurations can be realized by changing the location of a CLC layer. Low-power operation without the parallax problem can be achieved using the bistable switching of CLCs. We believe that the proposed devices are potential candidates for highly efficient transflective displays.

Optical configurations for nematic liquid crystal device switchable between reflective and transmissive modes.

We propose an optical configuration for a nematic liquid crystal (LC) device that is switchable between the reflective and the transmissive modes. By placing a reflective polarizer between the two LC layers, we obtain higher reflectance and reduce the parallax effect in the reflective mode. We can eliminate the parallax effect by using a wire-grid polarizer or other in-cell reflective polarizers. We expect that the proposed device can be used in various outdoor applications.

Two-dimensional photonic crystal color filter development.

Reflective color filters using two-dimensional photonic crystals based on sub-wavelength gratings were proposed and constructed. Using low-cost nanoimprint lithography, an amorphous silicon layer was deposited through the low-temperature PECVD process and patterned into two-dimensional structures. The isolated amorphous silicon patterns were readily crystallized using a multi-shot excimer laser annealing at low energy. A study of the close relationship between color filter reflectance and silicon pattern crystallinity is introduced. Theoretical and experimental results show that the proposed color filters have high reflectance and, moreover, decrease the dependence on incident angle compared to one-dimensional photonic crystal color filters.