6 research outputs found
Open Resonator Electric Spaser
The
inception of the plasmonic laser or spaser (surface plasmon
amplification by stimulated emission of radiation) concept in 2003
provides a solution for overcoming the diffraction limit of electromagnetic
waves in miniaturization of traditional lasers into the nanoscale.
From then on, many spaser designs have been proposed. However, all
existing designs use closed resonators. In this work, we use cavity
quantum electrodynamics analysis to theoretically demonstrate that
it is possible to design an electric spaser with an open resonator
or a closed resonator with much weak feedback in the extreme quantum
limit in an all-carbon platform. A carbon nanotube quantum dot plays
the role of a gain element, and Coulomb blockade is observed. Graphene
nanoribbons are used as the resonator, and surface plasmon polariton
field distribution with quantum electrodynamics features can be observed.
From an engineering perspective, our work makes preparations for integrating
spasers into nanocircuits and/or photodynamic therapy applications
Visualization 2: Optical Bloch oscillations and Zener tunneling of Airy beams in ionic-type photonic lattices
Optical Bloch oscillations of Airy beam in lattice 2 Originally published in Optics Express on 08 August 2016 (oe-24-16-18332
Visualization 1: Optical Bloch oscillations and Zener tunneling of Airy beams in ionic-type photonic lattices
Optical Bloch oscillations of Airy beam in lattice 1 Originally published in Optics Express on 08 August 2016 (oe-24-16-18332
Optical Anisotropy of Topologically Distorted Semiconductor Nanocrystals
Engineering
nanostructured optical materials via the purposeful distortion of
their constituent nanocrystals requires the knowledge of how various
distortions affect the nanocrystalsâ electronic subsystem and
its interaction with light. We use the geometric theory of defects
in solids to calculate the linear permittivity tensor of semiconductor
nanocrystals whose crystal lattice is arbitrarily distorted by imperfections
or strains. The result is then employed to systematically analyze
the optical properties of nanocrystals with spatial dispersion caused
by screw dislocations and Eshelby twists. We demonstrate that Eshelby
twists create gyrotropy in nanocrystals made of isotropic semiconductors
whereas screw dislocations can produce it only if the nanocrystal
material itself is inherently anisotropic. We also show that the dependence
of circular dichroism spectrum on the aspect ratio of dislocation-distorted
semiconductor nanorods allows resonant enhancing their optical activity
(at least by a factor of 2) and creating highly optically active nanomaterials
Optically Active Semiconductor Nanosprings for Tunable Chiral Nanophotonics
The
search for the optimal geometry of optically active semiconductor
nanostructures is making steady progress and has far-reaching benefits.
Yet the helical springlike shape, which is very likely to provide
a highly dissymmetric optical response, remains somewhat understudied
theoretically. Here we comprehensively analyze the optical activity
of semiconductor nanosprings using a fully quantum-mechanical model
of their electronic subsystem and taking into account the anisotropy
of their interaction with light. We show that the circular dichroism
of semiconductor nanosprings can exceed that of ordinary semiconductor
nanocrystals by a factor of 100 and be comparable to the circular
dichroism of metallic nanosprings. It is also demonstrated that nanosprings
can feature a total dissymmetry of optical response for certain ratios
between their length and coil height. The magnitude and sign of the
circular dichroism signal can be controlled by stretching or compressing
the nanosprings, which makes them a promising material base for optomechanical
sensors, polarization controllers, and other types of optically active
nanophotonic devices
Giant Plasmene Nanosheets, Nanoribbons, and Origami
We introduce <i>Plasmene</i>î¸ in analogy to grapheneî¸as free-standing, one-particle-thick, superlattice sheets of nanoparticles (âmeta-atomsâ) from the âplasmonic periodic tableâ, which has implications in many important research disciplines. Here, we report on a general bottom-up self-assembly approach to fabricate giant plasmene nanosheets (<i>i.e.</i>, plasmene with nanoscale thickness but with macroscopic lateral dimensions) as thin as âź40 nm and as wide as âź3 mm, corresponding to an aspect ratio of âź75â000. In conjunction with topâdown lithography, such robust giant nanosheets could be milled into one-dimensional nanoribbons and folded into three-dimensional origami. Both experimental and theoretical studies reveal that our giant plasmene nanosheets are analogues of graphene from the plasmonic nanoparticle family, simultaneously possessing unique structural features and plasmon propagation functionalities