[Show abstract][Hide abstract] ABSTRACT: The origin of omnidirectional band gaps in one-dimensional layered photonic structures which are aligned according to the generalized Kolakoski inflation rule are studied using the transfer matrix formalism. On their basis some particular designs of cascaded aperiodic heterostructures are proposed. It is found that the proposed cascaded structures stand out by the omnidirectional reflection bands which cover whole near-infrared spectral region.
Progress In Electromagnetics Research M 02/2015; 41:33-41.
[Show abstract][Hide abstract] ABSTRACT: We report on the optical induction of Fibonacci lattices in photorefractive
strontium barium niobate by use of Bessel beam waveguide-wise writing
techniques. Fibonacci elements A and B are used as lattice periods. We further
use the induced structures to execute probing experiments with variously
focused Gaussian beams in order to observe light confinement owing to the
quasiperiodic character of Fibonacci word sequences. Essentially, we show that
Gaussian beam expansion is just slowed down in Fibonacci lattices, as compared
with appropriate periodic lattices.
[Show abstract][Hide abstract] ABSTRACT: Quasi-crystal structures do not present a full spatial periodicity but are nevertheless constructed starting from deterministic generation rules. When made of different dielectric materials, they often possess fascinating optical properties, which lie between those of periodic photonic crystals and those of a random arrangement of scatterers. Indeed, they can support extended band-like states with pseudogaps in the energy spectrum, but lacking translational invariance, they also intrinsically feature a pattern of 'defects', which can give rise to critically localized modes confined in space, similar to Anderson modes in random structures. If used as laser resonators, photonic quasi-crystals open up design possibilities that are simply not possible in a conventional periodic photonic crystal. In this letter, we exploit the concept of a 2D photonic quasi crystal in an electrically injected laser; specifically, we pattern the top surface of a terahertz quantum-cascade laser with a Penrose tiling of pentagonal rotational symmetry, reaching 0.1-0.2% wall-plug efficiencies and 65 mW peak output powers with characteristic surface-emitting conical beam profiles, result of the rich quasi-crystal Fourier spectrum.
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