Bragg diffraction in thin 2D refractive index modulated semiconductor samples

Abstract

A very simple model has been developed to describe the diffractive properties of a crossed grating structure of the refractive index formed by a thin transmission grating recorded in a Bragg reflector. When the Bragg condition of the transmission grating coincides with the band edge of the reflection grating seen as a onedimensional photonic crystal, the diffraction efficiency and wavelength selectivity of the transmission grating are highly enhanced and a Bragg diffraction regime can be obtained, even in very thin samples. The model can be used to design micrometric very efficient new diffracting devices for optical signal processing.

Topological Dislocations for Plasmonic Mode Localization in Arrays of Nanoscale Rectangular Au Apertures: Implications for Optical Communications

“…The field of topological photonics − has gained much interest lately in nanophotonics and optical communication communities. , Topology , has, in fact, been recognized as a novel degree of freedom in light–matter interactions, as it provides an almost lossless medium for optical signals. Efficient light confinement, guiding, and localization have been achieved by using photonic crystal (PhC) optical systems with topological states. , These optical modes have emerged within the photonic band gap induced by the PhC periodicity at an interface between two or more regions with different topological phases. , The optical edge states were shown to be topology protected and propagated with negligible scattering losses, in analogy with currents in so-called topological insulators that have been recently discovered. , Modern nanofabrication techniques facilitate the realization of nanoscale periodic optical media with any desired geometry, which provides a practical advantage for the topology based nanophotonics with respect to classical index-modulated systems. , A special interest was focused on systems supporting surface plasmon (SP) , modesexcitations of the bound electric charges in the vicinity of a metal–insulator interface. , It has already been shown that these excitations are intrinsically topological in nature and represent an edge state − of two adjacent media with an abrupt sign change of the dielectric constant. Nevertheless, some further studies , have discussed the possibility of further localizing the SP modes within a metasurfacethe 2D equivalent of a metamaterial comprising a periodic structure with effective optical properties. − Most commonly, such a system is realized via nanometric apertures or particles periodically arranged on a metal surface.…”

“…14,15 Modern nanofabrication techniques facilitate the realization of nanoscale periodic optical media with any desired geometry, which provides a practical advantage for the topology based nanophotonics with respect to classical index-modulated systems. 12, 16 A special interest was focused on systems supporting surface plasmon (SP) 17,18 modesexcitations of the bound electric charges in the vicinity of a metal−insulator interface. 19,20 It has already been shown that these excitations are intrinsically topological in nature and represent an edge state 21−23 of two adjacent media with an abrupt sign change of the dielectric constant.…”

Topological dislocations for plasmonic mode localization

“…The optical edge states were shown to be topology protected and propagated with negligible scattering losses, in analogy with currents in so-called topological insulators that have been recently discovered 13,14 . Modern nano-fabrication techniques facilitate the realization of nanoscale periodic optical media with any desired geometry, which provides a practical advantage for the topology based nanophotonics with respect to a classical index-modulated systems 11,15 . A special interest was focused on systems supporting surface plasmon (SP) 16,17 modes -excitations of the bound electric charges in the vicinity of a metal-insulator interface.…”