Innovative approaches and tools play an important role in shaping design, characterization and optimization for the field of photonics. As a subset of machine learning that learns multilevel ...abstraction of data using hierarchically structured layers, deep learning offers an efficient means to design photonic structures, spawning data-driven approaches complementary to conventional physics- and rule-based methods. Here, we review recent progress in deep-learning-based photonic design by providing the historical background, algorithm fundamentals and key applications, with the emphasis on various model architectures for specific photonic tasks. We also comment on the challenges and perspectives of this emerging research direction.The application of deep learning to the design of photonic structures and devices is reviewed, including algorithm fundamentals.
Overcoming quantum decoherence with plasmonics Bogdanov, Simeon I; Boltasseva, Alexandra; Shalaev, Vladimir M
Science (American Association for the Advancement of Science),
05/2019, Letnik:
364, Številka:
6440
Journal Article
Recenzirano
The use of nanoscale plasmonic metamaterials can optimize photon-matter interactions
Photons occupy a special place as carriers of quantum information because they propagate information at the speed ...of light, with almost zero cross-talk, and interact relatively weakly with matter. They are primary candidates for implementing quantum networks (
1
), which are essential for both secure communication and transmission of quantum information. Nonclassical states of light (such as squeezed states) are also used in quantum simulation and emerging quantum sensing approaches. However, the robustness of photons as carriers of quantum information is a double-edged sword. In order to produce single photons or make them interact with each other, light must couple with matter. Photonic technologies, especially those implemented with nanoscale plasmonic metamaterials, can enable these interactions and help realize the full potential of photons in quantum information technology.
Low-Loss Plasmonic Metamaterials Boltasseva, Alexandra; Atwater, Harry A.
Science (American Association for the Advancement of Science),
01/2011, Letnik:
331, Številka:
6015
Journal Article
Recenzirano
New materials are being developed that meet the requirements for nanoscale photonics.
Metamaterials (MMs) are artificial, engineered materials with rationally designed compositions and arrangements ...of nanostructured building blocks. These materials can be tailored for almost any application because of their extraordinary response to electromagnetic, acoustic, and thermal waves that transcends the properties of natural materials (
1
–
3
). The astonishing MM-based designs and demonstrations range from a negative index of refraction, focusing and imaging with sub-wavelength resolution, invisibility cloaks, and optical black holes to nanoscale optics, data processing, and quantum information applications (
3
). Metals have traditionally been the material of choice for the building blocks, but they suffer from high resistive losses—even metals with the highest conductivities, silver and gold, exhibit excessive losses at optical frequencies that restrict the development of devices in this frequency range. The development of new materials for low-loss MM components and telecommunication devices is therefore required.
Abstract
Over the past years, broadband achromatic metalenses have been intensively studied due to their great potential for applications in consumer and industry products. Even though significant ...progress has been made, the efficiency of technologically relevant silicon metalenses is limited by the intrinsic material loss above the bandgap. In turn, the recently proposed achromatic metalens utilizing transparent, high-index materials such as titanium dioxide has been restricted by the small thickness and showed relatively low focusing efficiency at longer wavelengths. Consequently, metalens-based optical imaging in the biological transparency window has so far been severely limited. Herein, we experimentally demonstrate a polarization-insensitive, broadband titanium dioxide achromatic metalens for applications in the near-infrared biological imaging. A large-scale fabrication technology has been developed to produce titanium dioxide nanopillars with record-high aspect ratios featuring pillar heights of 1.5 µm and ~90° vertical sidewalls. The demonstrated metalens exhibits dramatically increased group delay range, and the spectral range of achromatism is substantially extended to the wavelength range of 650–1000 nm with an average efficiency of 77.1%–88.5% and a numerical aperture of 0.24–0.1. This research paves a solid step towards practical applications of flat photonics.
Refractory Plasmonics Guler, Urcan; Boltasseva, Alexandra; Shalaev, Vladimir M.
Science (American Association for the Advancement of Science),
04/2014, Letnik:
344, Številka:
6181
Journal Article
Recenzirano
Stable at high temperatures, refractory plasmonic materials could boost existing optoelectronic technologies.
Refractory materials are defined as those with a high melting point and chemical ...stability at temperatures above 2000°C. Applications based on refractory materials, usually nonmetallic, span a wide range of areas including industrial furnaces, space shuttle shields, and semiconductor technology. Metals have also been studied as refractories; however, the optical properties of those metals that have been tried for high-temperature applications were not good enough to be used in plasmonic applications (these are almost entirely based on noble metals, which are not good refractories). Refractory materials that exhibit reasonably good plasmonic behavior would undoubtedly enable new devices and boost such existing applications as heat-assisted magnetic recording (HAMR) (
1
), solar/thermophotovoltaics (S/TPV) (
2
), plasmon-assisted chemical vapor deposition (
3
), solar thermoelectric generators (
4
), and nanoscale heat transfer systems (
5
).
Materials research plays a vital role in transforming breakthrough scientific ideas into next‐generation technology. Similar to the way silicon revolutionized the microelectronics industry, the ...proper materials can greatly impact the field of plasmonics and metamaterials. Currently, research in plasmonics and metamaterials lacks good material building blocks in order to realize useful devices. Such devices suffer from many drawbacks arising from the undesirable properties of their material building blocks, especially metals. There are many materials, other than conventional metallic components such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent conducting oxides, perovskite oxides, metal nitrides, silicides, germanides, and 2D materials such as graphene. This review provides a summary of the recent developments in the search for better plasmonic materials and an outlook of further research directions.
Breakthrough ideas in plasmonics and metamaterials require good material building blocks to realize useful devices. Currently, plasmonic and metamaterial devices suffer from many drawbacks arising from the undesirable properties of their material building blocks, especially the metallic components. There are many materials, other than conventional metallic components, such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability.
Plasmonics aims at combining features of photonics and electronics by coupling photons with a free-electron gas, whose subwavelength oscillations (surface plasmons) enable manipulation of light at ...the nanoscale and engender the exciting properties of optical metamaterials. Plasmonics is facing a grand challenge of overcoming metal losses impeding its progress. We reflect on the reasons why subwavelength confinement and loss are intimately intertwined and investigate the physics of loss in conductors beyond the conventional Drude model. We suggest that commonly used noble metals may not be the best materials for plasmonics and describe alternate materials such as transparent conducting oxides and transition metal nitrides. We consider the prospects of compensating the loss with gain materials and conclude that the so-far elusive solution to the loss obstacle lies in finding better materials with lower losses.
Over the past years, photonic metasurfaces have demonstrated their remarkable and diverse capabilities in advanced control over light propagation. Here, we demonstrate that these artificial films of ...deeply subwavelength thickness also offer new unparalleled capabilities in decreasing the overall dimensions of integrated optical systems. We propose an original approach of embedding a metasurface inside an optical cavity-one of the most fundamental optical elements-to drastically scale-down its thickness. By modifying the Fabry-Pérot interferometric principle, this methodology is shown to reduce the metasurface-based nanocavity thickness below the conventional λ/(2n) minimum. In addition, the nanocavities with embedded metasurfaces can support independently tunable resonances at multiple bands. As a proof-of-concept, using nanostructured metasurfaces within 100-nm nanocavities, we experimentally demonstrate high spatial resolution colour filtering and spectral imaging. The proposed approach can be extrapolated to compact integrated optical systems on-a-chip such as VCSEL's, high-resolution spatial light modulators, imaging spectroscopy systems, and bio-sensors.
For nearly two decades, researchers in the field of plasmonics
-which studies the coupling of electromagnetic waves to the motion of free electrons near the surface of a metal
-have sought to realize ...subwavelength optical devices for information technology
, sensing
, nonlinear optics
, optical nanotweezers
and biomedical applications
. However, the electron motion generates heat through ohmic losses. Although this heat is desirable for some applications such as photo-thermal therapy, it is a disadvantage in plasmonic devices for sensing and information technology
and has led to a widespread view that plasmonics is too lossy to be practical. Here we demonstrate that the ohmic losses can be bypassed by using 'resonant switching'. In the proposed approach, light is coupled to the lossy surface plasmon polaritons only in the device's off state (in resonance) in which attenuation is desired, to ensure large extinction ratios between the on and off states and allow subpicosecond switching. In the on state (out of resonance), destructive interference prevents the light from coupling to the lossy plasmonic section of a device. To validate the approach, we fabricated a plasmonic electro-optic ring modulator. The experiments confirm that low on-chip optical losses, operation at over 100 gigahertz, good energy efficiency, low thermal drift and a compact footprint can be combined in a single device. Our result illustrates that plasmonics has the potential to enable fast, compact on-chip sensing and communications technologies.
PDF
