425 research outputs found
Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator
We propose new designs of plasmonic modulators, which can be utilized for
dynamic signal switching in photonic integrated circuits. We study performance
of plasmonic waveguide modulator with bismuth ferrite as an active material.
The bismuth ferrite core is sandwiched between metal plates
(metal-insulator-metal configuration), which also serve as electrodes so that
the core changes its refractive index under applied voltage by means of partial
in-plane to out-of-plane reorientation of ferroelectric domains in bismuth
ferrite. This domain switch results in changing of propagation constant and
absorption coefficient, and thus either phase or amplitude control can be
implemented. Efficient modulation performance is achieved because of high field
confinement between the metal layers, as well as the existence of mode cut-offs
for particular values of the core thickness, making it possible to control the
signal with superior modulation depth. For the phase control scheme, {\pi}
phase shift is provided by 0.8-{\mu}m length device having propagation losses
0.29 dB/{\mu}m. For the amplitude control, we predict up to 38 dB/{\mu}m
extinction ratio with 1.2 dB/{\mu}m propagation loss. In contrast to previously
proposed active materials, bismuth ferrite has nearly zero material losses, so
bismuth ferrite based modulators do not bring about additional decay of the
propagating signal
Roadmap on optical energy conversion
For decades, progress in the field of optical (including solar) energy conversion was dominated by advances in the conventional concentrating optics and materials design. In recent years, however, conceptual and technological breakthroughs in the fields of nanophotonics and plasmonics combined with a better understanding of the thermodynamics of the photon energy-conversion processes reshaped the landscape of energy-conversion schemes and devices. Nanostructured devices and materials that make use of size quantization effects to manipulate photon density of states offer a way to overcome the conventional light absorption limits. Novel optical spectrum splitting and photon-recycling schemes reduce the entropy production in the optical energy-conversion platforms and boost their efficiencies. Optical design concepts are rapidly expanding into the infrared energy band, offering new approaches to harvest waste heat, to reduce the thermal emission losses, and to achieve noncontact radiative cooling of solar cells as well as of optical and electronic circuitries. Light–matter interaction enabled by nanophotonics and plasmonics underlie the performance of the third- and fourth-generation energy-conversion devices, including up- and down-conversion of photon energy, near-field radiative energy transfer, and hot electron generation and harvesting. Finally, the increased market penetration of alternative solar energy-conversion technologies amplifies the role of cost-driven and environmental considerations. This roadmap on optical energy conversion provides a snapshot of the state of the art in optical energy conversion, remaining challenges, and most promising approaches to address these challenges. Leading experts authored 19 focused short sections of the roadmap where they share their vision on a specific aspect of this burgeoning research field. The roadmap opens up with a tutorial section, which introduces major concepts and terminology. It is our hope that the roadmap will serve as an important resource for the scientific community, new generations of researchers, funding agencies, industry experts, and investors.United States. Department of Energy (DE-AC36-086038308
Interfacing single photons and single quantum dots with photonic nanostructures
Photonic nanostructures provide means of tailoring the interaction between
light and matter and the past decade has witnessed a tremendous experimental
and theoretical progress in this subject. In particular, the combination with
semiconductor quantum dots has proven successful. This manuscript reviews
quantum optics with excitons in single quantum dots embedded in photonic
nanostructures. The ability to engineer the light-matter interaction strength
in integrated photonic nanostructures enables a range of fundamental
quantum-electrodynamics experiments on, e.g., spontaneous-emission control,
modified Lamb shifts, and enhanced dipole-dipole interaction. Furthermore,
highly efficient single-photon sources and giant photon nonlinearities may be
implemented with immediate applications for photonic quantum-information
processing. The review summarizes the general theoretical framework of photon
emission including the role of dephasing processes, and applies it to photonic
nanostructures of current interest, such as photonic-crystal cavities and
waveguides, dielectric nanowires, and plasmonic waveguides. The introduced
concepts are generally applicable in quantum nanophotonics and apply to a large
extent also to other quantum emitters, such as molecules, nitrogen vacancy
ceters, or atoms. Finally, the progress and future prospects of applications in
quantum-information processing are considered.Comment: Updated version resubmitted to Reviews of Modern Physic
Trends in Nanophotonics-Enabled Optofluidic Biosensors
Optofluidic sensors integrate photonics with micro/nanofluidics to realize compact devices for the label-free detection of molecules and the real-time monitoring of dynamic surface binding events with high specificity, ultrahigh sensitivity, low detection limit, and multiplexing capability. Nanophotonic structures composed of metallic and/or dielectric building blocks excel at focusing light into ultrasmall volumes, creating enhanced electromagnetic near-fields ideal for amplifying the molecular signal readout. Furthermore, fluidic control on small length scales enables precise tailoring of the spatial overlap between the electromagnetic hotspots and the analytes, boosting light-matter interaction, and can be utilized to integrate advanced functionalities for the pre-treatment of samples in real-world-use cases, such as purification, separation, or dilution. In this review, the authors highlight current trends in nanophotonics-enabled optofluidic biosensors for applications in the life sciences while providing a detailed perspective on how these approaches can synergistically amplify the optical signal readout and achieve real-time dynamic monitoring, which is crucial in biomedical assays and clinical diagnostics
DNA nanotechnology-enabled chiral plasmonics: from static to dynamic
In this Account, we discuss a variety of static and dynamic chiral plasmonic
nanostructures enabled by DNA nanotechnology. In the category of static
plasmonic systems, we first show chiral plasmonic nanostructures based on
spherical AuNPs, including plasmonic helices, toroids, and tetramers. To
enhance the CD responses, anisotropic gold nanorods with larger extinction
coefficients are utilized to create chiral plasmonic crosses and helical
superstructures. Next, we highlight the inevitable evolution from static to
dynamic plasmonic systems along with the fast development of this
interdisciplinary field. Several dynamic plasmonic systems are reviewed
according to their working mechanisms.Comment: 7 figure
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