An optical diode (OD) and its application based on the photonic band-gap (PBG) property of chiral photonic crystals are presented. The OD is constructed from wave-plates and cholesteric liquid crystals with two different pitches. The component is polarization sensitive and exhibits passive anisotropic transmission analogous to the electronic diode. The non-reciprocal transmission of linearly polarized light at the different PBG regions is discussed. A new scheme of a color-separating system with the OD is proposed. The OD behavior constitutes the operational mechanism for a color splitter.
Abstract-Light extraction efficiency of light-emitting diodes (LEDs) based on various photonic crystal (PhC) structures is investigated in this study. By using the plane wave method and the finite element method, the influence of several factors on the enhancement of light extraction is discussed, including lattice type, the density of states from a photonic band diagram, the ratio of cylinder radius and lattice constant, and the thickness of a PHC pattern. Some rules are given for the practical implementation of an optimized PhC-based LED with higher light extraction efficiency. In the simulation results, the maximum enhancement of the extraction efficiency could be by a factor of approximately 2.8 for the optimized Archimedean tiling pattern in the LED device emitting at the center wavelength of 530 nm. However, with the use of optimized PhC structures, the square and triangular lattices reveal enhancements of ∼ 1.7 and ∼ 1.5, respectively. The extraction efficiency of the Archimedean PhC LED is much greater than that of the regular lattice PhC LED.
Abstract-Light concentrating structures with three-dimensional photonic crystals (3D PhCs) for solar cell applications are investigated via simulation. The 3D opal PhCs are suggested as an intermediate layer in the concentrator system for solar cells. It is found that the light absorption is significantly enhanced due to the adding of diffractive effects of PhCs to the concentrator. Three types of PhCs are considered in four scenarios to verify the absorption enhancement by such a light concentrating structure. Our calculations show that the face-centered cubic PhC can create an absorbing efficiency superior to the others under a specified lattice orientation pointing to the sun, which results in an enhancement factor of 1.56 in absorption for the 500-1100 nm spectral range.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.