9 research outputs found
Modeling open nanophotonic systems using the Fourier modal method: Generalization to 3D Cartesian coordinates
Recently, an open geometry Fourier modal method based on a new combination of
an open boundary condition and a non-uniform -space discretization was
introduced for rotationally symmetric structures providing a more efficient
approach for modeling nanowires and micropillar cavities [J. Opt. Soc. Am. A
33, 1298 (2016)]. Here, we generalize the approach to three-dimensional (3D)
Cartesian coordinates allowing for the modeling of rectangular geometries in
open space. The open boundary condition is a consequence of having an infinite
computational domain described using basis functions that expand the whole
space. The strength of the method lies in discretizing the Fourier integrals
using a non-uniform circular "dartboard" sampling of the Fourier space. We
show that our sampling technique leads to a more accurate description of the
continuum of the radiation modes that leak out from the structure. We also
compare our approach to conventional discretization with direct and inverse
factorization rules commonly used in established Fourier modal methods. We
apply our method to a variety of optical waveguide structures and demonstrate
that the method leads to a significantly improved convergence enabling more
accurate and efficient modeling of open 3D nanophotonic structures
Photonic “hourglass” design for efficient quantum light emission
International audienceWe propose a novel “hourglass”-shaped design for highly efficient generation and collection of quantum light. The design features a quantum dot in a photonic nanowire sandwiched between tapered Bragg reflectors. For a Purcell factor of 9, the design features a spontaneous emission coupling of0.993 to the cavity mode enabled by the strong dielectric screening of radiation modes. Thanks to a highly reflecting bottom mirror, we furthermore demonstrate a collection efficiency of 0.95 to a Gaussian profile. Finally, this photonic structure features a broad operation bandwidth, as large as 11 nm
Cavity-waveguide interplay in optical resonators and its role in optimal single-photon sources
Interfacing solid-state emitters with photonic structures is a key strategy
for developing highly efficient photonic quantum technologies. Such structures
are often organised into two distinct categories: nanocavities and waveguides.
However, any realistic nanocavity structure simultaneously has characteristics
of both a cavity and waveguide, which is particularly pronounced when the
cavity is constructed using low-reflectivity mirrors in a waveguide structure
with good transverse light confinement. In this regime, standard cavity quantum
optics theory breaks down, as the waveguide character of the underlying
dielectric is only weakly suppressed by the cavity mirrors. By consistently
treating the photonic density of states of the structure, we provide a
microscopic description of an emitter including the effects of phonon
scattering over the full transition range from waveguide to cavity. This
generalised theory lets us identify an optimal regime of operation for
single-photon sources in optical nanostructures, where cavity and waveguide
effects are concurrently exploited
A nanowire optical nanocavity for broadband enhancement of spontaneous emission
International audienceTo deliver an optimal performance for photonic quantum technologies, semiconductor quantum dots should be integrated in a carefully designed photonic structure. Here, we introduce a nanowire optical nanocavity designed for free-space emission. Thanks to its ultrasmall mode volume, this simple structure offers a large acceleration of spontaneous emission (predicted Purcell factor of 6.3) that is maintained over a 30-nm bandwidth. In addition, a dielectric screening effect strongly suppresses the emission into the 3D continuum of radiation modes. The fraction of spontaneous emission funneled into the cavity mode reaches 0.98 at resonance and exceeds 0.95 over a 100-nm spectral range. Close-to-optimal collection efficiency is maintained over an equivalent bandwidth and reaches a predicted value of 0.54 at resonance for a first lens with a numerical aperture (NA) of 0.75. As a first experimental demonstration of this concept, we fabricate an Au–SiO2–GaAs device embedding isolated InAs quantum dots. We measure a maximal acceleration of spontaneous emission by a factor as large as 5.6 and a bright quantum dot emission (collection efficiency of 0.35 into NA¼0.75). This nanowire cavity constitutes a promising building block to realize advanced sources of quantum light for a broad range of material systems
A nanowire optical nanocavity for broadband enhancement of spontaneous emission
International audienceTo deliver an optimal performance for photonic quantum technologies, semiconductor quantum dots should be integrated in a carefully designed photonic structure. Here, we introduce a nanowire optical nanocavity designed for free-space emission. Thanks to its ultrasmall mode volume, this simple structure offers a large acceleration of spontaneous emission (predicted Purcell factor of 6.3) that is maintained over a 30-nm bandwidth. In addition, a dielectric screening effect strongly suppresses the emission into the 3D continuum of radiation modes. The fraction of spontaneous emission funneled into the cavity mode reaches 0.98 at resonance and exceeds 0.95 over a 100-nm spectral range. Close-to-optimal collection efficiency is maintained over an equivalent bandwidth and reaches a predicted value of 0.54 at resonance for a first lens with a numerical aperture (NA) of 0.75. As a first experimental demonstration of this concept, we fabricate an Au–SiO2–GaAs device embedding isolated InAs quantum dots. We measure a maximal acceleration of spontaneous emission by a factor as large as 5.6 and a bright quantum dot emission (collection efficiency of 0.35 into NA¼0.75). This nanowire cavity constitutes a promising building block to realize advanced sources of quantum light for a broad range of material systems