Omnidirectional Photonic Bandgap in Two-dimensional Photonic Quasicrystal Made of Near-Transparent Dielectric Material

Complete bandgap for all-dielectric photonic crystals in the microwave region can be obtained only by using high-contrast materials. This requires the usage of dielectric materials with high relative permittivity coefficient. In this paper, we study, both numerically and experimentally, a two-dimensional all-dielectric photonic quasicrystal made of polyurethane foam, which is considered in all microwave applications as a transparent material. The quasicrystal structure having an omnidirectional two-dimensional bandgap is mathematically generated by the direct inscription of Bragg’s peaks of the structure in the reciprocal space. The sample of the quasicrystal was manufactured on CNC (computer numerical controlled) milling machine out of foam with very low dielectric permittivity of 1.254. The numerical simulations and the experimental study are in good agreement with the theoretical model.

Polymeric Photonic Quasicrystal: Octonacci Sequence and Elasto-optic Effect

Here we would like to discuss the light transmission modulation by the one-dimensional polymeric quasi-multilayer which is formed according to substitutional generalized Octonacci with PMMA and PS as the constituent materials. In particular, we will present some theoretical findings using the well-known transfer matrix method. PBG inter-band spacing and depth can be managed by choosing the appropriate generation number. The number of PBGs is the same while increasing in the generation number and are shifted symmetrically towards the designed frequency. It also reveals the aroused forbidden frequency band can be manipulated by changing the applied hydrostatic pressure and the thickness of the constituent polymeric materials. The increase in pressure shows a blue shift in the PBGs while the increase in thickness of the polymeric material provides a redshift to PBGs. The proposed structure could be another possible system for optical device design specially multi-band tunable optical reflectors.

Multicolor Emission from Ultraviolet GaN-Based Photonic Quasicrystal Nanopyramid Structure with Semipolar InxGa1−xN/GaN Multiple Quantum Wells

In this study, we demonstrated large-area high-quality multi-color emission from the 12-fold symmetric GaN photonic quasicrystal nanorod device which was fabricated using the nanoimprint lithography technology and multiple quantum wells regrowth procedure. High-efficiency blue and green color emission wavelengths of 460 and 520 nm from the regrown InxGa1−xN/GaN multiple quantum wells were observed under optical pumping conditions. To confirm the strong coupling between the quantum well emissions and the photonic crystal band-edge resonant modes, the finite-element method was applied to perform a simulation of the 12-fold symmetry photonic quasicrystal lattices.

Multicolor Emission from Ultraviolet GaN-based Photonic Quasicrystal Nanopyramid Structure with Semipolar InxGa1-xN/GaN Multiple Quantum Wells

In this study, we demonstrated large-area high quality multi-color emission from the 12-fold symmetric GaN photonic quasicrystal nanorod device which was fabricated using the nanoimprint lithography technology and multiple quantum wells regrowth procedure. High-efficiency blue and green color emission wavelengths of 460 and 520 nm from the regrown InxGa1−xN/GaN multiple quantum wells were observed under optical pumping conditions. To confirm the strongly coupling between the quantum well emissions and the photonic crystal band-edge resonant modes, the finite-element method (FEM) was applied to perform a simulation of the 12-fold symmetry photonic quasicrystal lattices.