Role Of Photons Research Articles

Heat Pulses in Electron Quantum Optics.

Electron quantum optics aims to realize ideas from the quantum theory of light with the role of photons being played by charge pulses in electronic conductors. Experimentally, the charge pulses are excited by time-dependent voltages; however, one could also generate heat pulses by heating and cooling an electrode. Here, we explore this intriguing idea by formulating a Floquet scattering theory of heat pulses in mesoscopic conductors. The adiabatic emission of heat pulses leads to a heat current that in linear response is given by the thermal conductance quantum. However, we also find a high-frequency component, which ensures that the fluctuation-dissipation theorem for heat currents, whose validity has been debated, is fulfilled. The heat pulses are uncharged, and we probe their electron-hole content by evaluating the partition noise in the outputs of a quantum point contact. We also employ a Hong-Ou-Mandel setup to examine if the pulses bunch or antibunch. Finally, to generate an electric current, we use a Mach-Zehnder interferometer that breaks the electron-hole symmetry and thereby enables a thermoelectric effect. Our Letter paves the way for systematic investigations of heat pulses in mesoscopic conductors, and it may stimulate future experiments.

Unconventional magnetism mediated by spin-phonon-photon coupling

Magnetic order typically emerges due to the short-range exchange interaction between the constituent electronic spins. Recent discoveries have found a crucial role for spin-phonon coupling in various phenomena from optical ultrafast magnetization switching to dynamical control of the magnetic state. Here, we demonstrate theoretically the emergence of a biquadratic long-range interaction between spins mediated by their coupling to phonons hybridized with vacuum photons into polaritons. The resulting ordered state enabled by the exchange of virtual polaritons between spins is reminiscent of superconductivity mediated by the exchange of virtual phonons. The biquadratic nature of the spin-spin interaction promotes ordering without favoring ferro- or antiferromagnetism. It further makes the phase transition to magnetic order a first-order transition, unlike in conventional magnets. Consequently, a large magnetization develops abruptly on lowering the temperature which could enable magnetic memories admitting ultralow-power thermally-assisted writing while maintaining a high data stability. The role of photons in the phenomenon further enables an in-situ static control over the magnetism. These unique features make our predicted spin-spin interaction and magnetism highly unconventional paving the way for novel scientific and technological opportunities.

The temporal dynamics of nonlocal plasmonic nanoparticle under the ultrashort pulses

Modern plasmonics plays a crucial role in photonics and optics, and paves a way for a variety of emerging applications. Since the stationary behavior of plasmonic nanoparticles is quite well studied, the quantum-driven ultrafast response of ultra-small particles in specific electromagnetic regimes attract ever-increasing attentions nowadays. In this paper, we investigate the temporal dynamics of the plasmonic nanoparticles involving nonlocal effect under the illumination by an external ultrashort pulse. We find that the intensity of the corresponding dipole moment can be globally suppressed and the magnitude of the time-shift decreases with the increase of nonlocality. In addition, we observe large decay rate and small oscillation period when the nonlocality is taken into account for quite small duration time near (or below) the surface plasmon resonant frequencies. Further discussion reveals that the time-shift can be either positive or negative because of the emergence of abnormal dispersion relationship. These reshaping on dipole moment in time domain may be applicable in the modulation on the ultrashort signals of nanophotonic devices.

Improving the nonlinear electro-optical responses of doped nematic liquid crystals with chiral dopants

Liquid crystals with considerable optical and electro-optical responses play important roles in photonics and optoelectronics. In this research, the electro-optical responses of pure and doped nematic liquid crystal with left-handed S-1011 chiral dopant with different percentages were investigated at different temperatures for the first time. According to the results, nematic liquid crystal with 4 wt% of chiral dopant indicates high electro-optical Kerr constat and third-order nonlinear susceptibility. In this case, various molecular interactions enhance the average order of nematic liquid crystal. By increasing the temperature, gradually the Kerr constant is deecreased, but this decreasing is slow for liquid crystal with 9 wt% of chiral dopant. Moreover, the temperature dependence of Kerr constant was used for calculating the pre-transition temperature. Therefore, these results provide a precise and simple method for improving the electro-optical responses of a nematic liquid crystal, which is an important step in the design of optoelectronic devices.

Shining a Light on Cancer-Photonics in Microfluidic Tumor Modeling and Biosensing.

Microfluidic platforms represent a powerful approach to miniaturizing important characteristics of cancers, improving in vitro testing by increasing physiological relevance. Different tools can manipulate cells and materials at the microscale, but few offer the efficiency and versatility of light and optical technologies. Moreover, light-driven technologies englobe a broad toolbox for quantifying critical biological phenomena. Herein, the role of photonics in microfluidic 3D cancer modeling and biosensing from three major perspectives is reviewed. First, optical-driven technologies are looked upon, as these allow biomaterials and living cells to be manipulated with microsized precision and present opportunities to advance 3D microfluidic models by engineering cancer microenvironments' hallmarks, such as their architecture, cellular complexity, and vascularization. Second, the growing field of optofluidics is discussed, exploring how optical tools can directly interface microfluidic chips, enabling the extraction of relevant biological data, from single fluorescent signals to the complete 3D imaging of diseased cells within microchannels. Third, advances in optical cancer biosensing are reviewed, focusing on how light-matter interactions can detect biomarkers, rare circulating tumor cells, and cell-derived structures such as exosomes. Photonic technologies' current challenges and caveats in microfluidic 3D cancer models are overviewed, outlining future research avenues that may catapult the field.

A New Way to Predict the Efficiency of Optical Limiters without Providing an Experiment: Processing of TDDFT Calculations for the Case of Pure Two-Photon Absorption.

Laser-power-limiting devices play a predominant role in photonics because of their potential for protecting human eyes and optical devices that are sensitive to intense laser beams. This paper describes a new methodology for predicting the efficiency of optical limiting based on electric-field-induced changes in absorption spectra calculated with the TDDFT quantum-chemical method. Analytical equations are derived to evaluate the optical thresholds and speed of switching on, the dynamic range, and the degree of nonlinear attenuation of the radiation fluxes for the case of two-photon absorption. Thus, the researcher does not need to conduct costly experiments to evaluate the suitability of nonlinear absorbers for the creation of optical limiters. The possibility of developing a forecasting model is demonstrated by an example of a series of stable slipped-cofacial phthalocyanine J-type dimers, which were synthesized and investigated previously.

Facet Selectivity Guided Assembly of Nanoarchitectures onto Two‐Dimensional Metal–Organic Framework Nanosheets

AbstractFacet‐selective nanostructures in living systems usually exhibit outstanding optical and enzymatic properties, playing important roles in photonics, matter exchange, and biocatalysis. Bioinspired construction of facet‐selective nanostructures offers great opportunities for sophisticated nanomaterials, but remains a formidable task. We have developed a macromolecule‐mediated strategy for the assembly of upconversion nanoparticles (UCNPs)/two‐dimensional metal–organic frameworks (2DMOFs) heterostructures with facet selectivity. Both experimental and theoretical results demonstrate that polyvinylpyrrolidone (PVP) can be utilized as an interface‐selective mediator to further promote the facet‐selective assembly of MOFs onto the surface of UCNPs. The UCNPs/2DMOFs nanostructures with facet selectivity display specific optical properties and show great advantages in anti‐counterfeiting. Our demonstration of UCNPs/2DMOFs provides a vivid example for the controlled fabrication of facet‐selective nanostructures and can promote the development of advanced functional materials for applications in biosensing, energy conversion, and information assurance.

Spontaneous symmetry breaking of dissipative optical solitons in a two-component Kerr resonator

Dissipative solitons are self-localized structures that can persist indefinitely in open systems driven out of equilibrium. They play a key role in photonics, underpinning technologies from mode-locked lasers to microresonator optical frequency combs. Here we report on experimental observations of spontaneous symmetry breaking of dissipative optical solitons. Our experiments are performed in a nonlinear optical ring resonator, where dissipative solitons arise in the form of persisting pulses of light known as Kerr cavity solitons. We engineer symmetry between two orthogonal polarization modes of the resonator and show that the solitons of the system can spontaneously break this symmetry, giving rise to two distinct but co-existing vectorial solitons with mirror-like, asymmetric polarization states. We also show that judiciously applied perturbations allow for deterministic switching between the two symmetry-broken dissipative soliton states. Our work delivers fundamental insights at the intersection of multi-mode nonlinear optical resonators, dissipative structures, and spontaneous symmetry breaking, and expands upon our understanding of dissipative solitons in coherently driven Kerr resonators.

Metalens for Generating a Customized Vectorial Focal Curve.

Three-dimensional (3D) light fields with spatially inhomogeneous polarization and intensity distributions play an increasingly important role in photonics due to their peculiar optical features and extra degrees of freedom for carrying information. However, it is very challenging to simultaneously control the intensity profile and polarization profile in an arbitrary manner. Here we experimentally demonstrate a metalens that can focus light into an arbitrarily shaped focal curve with a predefined polarization distribution. The efficacy of this approach is exemplified through the demonstration of focused curves in 3D space ranging from simple shapes such as a circle to topologically nontrivial objects such as a 3D knot with controlled local polarization states. This powerful control of the light field would be technically challenging with their conventional counterparts. Our demonstration may find applications in beam engineering and integration optics.

Photons detected in the active nerve by photographic technique

The nervous system is one of the most complex expressions of biological evolution. Its high performance mostly relies on the basic principle of the action potential, a sequential activation of local ionic currents along the neural fiber. The implications of this essentially electrical phenomenon subsequently emerged in a more comprehensive electromagnetic perspective of neurotransmission. Several studies focused on the possible role of photons in neural communication and provided evidence of the transfer of photons through myelinated axons. A hypothesis is that myelin sheath would behave as an optical waveguide, although the source of photons is controversial. In a previous work, we proposed a model describing how photons would arise at the node of Ranvier. In this study we experimentally detected photons in the node of Ranvier by Ag+ photoreduction measurement technique, during electrically induced nerve activity. Our results suggest that in association to the action potential a photonic radiation takes place in the node.

Analysis of Compact Silicon Photonic Hybrid Ring External Cavity (SHREC) Wavelength-Tunable Laser Diodes Operating From 1881–1947 nm

The “ $2~\mu \text{m}$ waveband”, specifically the $1.9~\mu \text{m}$ wavelength region, is playing an increasingly imperative role in photonics. Development into compact tunable light sources operating at the wavelength region can unlock numerous technological applications. Instances, while not exhaustive, include alleviating the capacity load in fiber communications, H2O spectroscopy, optical logic, signal processing as well as enabling the optical Kerr effect on silicon. Silicon photonics is a disruptive technology. Through mature silicon processing, recent developments suggest that silicon will emerge as the workhorse of integrated optics. While the realization of a monolithic light source has proved to be challenging, the hybrid/heterogenous Si platforms, consisting of silicon and III-V materials, has stepped to the fore. In this work, we present the study of Vernier-based hybrid silicon photonic wavelength-tunable lasers with an operating range of 1881–1947 nm (66 nm), subject to different coupling gaps (Gapmrr) between the silicon microring resonators (MRRs) and bus waveguide. Wavelength tuning functionality is enabled via the thermo-optic effect of MRRs. Gapmrr, being the smallest feature in the assemble, is highly influential to the characteristics of the SHREC. As such, trends in hybrid laser performance with respect to Gapmrr are measured and analyzed. Slope efficiency, laser output power and side-mode suppression ratio of 0.232 W/A, 28 mW and 42 dB respectively are obtained across the developed lasers. Through the design of the Vernier spectrum and Gapmrr, tuning of laser wavelength from 1881–1947 nm can be achieved by applying only 47.2 mW of thermal power to a single MRR.

Highly crystallized transparent luminescent glass ceramics containing dual-phase ZnGa2O4 spinel and α-Zn2SiO4 willemite nanocrystals

Preparation of transparent glass ceramics (TGCs) with a high crystallinity has become a new research trend recently. In the present work, TGCs containing dual-phase ZnGa2O4 spinel and α-Zn2SiO4 willemite nanocrystals (NCs) are obtained simply by controlled crystallization from a cost-effective quaternary glass system SiO2-Ga2O3-ZnO-Na2O. The TGCs have a high crystallinity 85 ± 5 % and remain transparent in the visible light region. Crystallization behaviors of the TGCs have been revealed using high-resolution transmission electron microscopy (HR-TEM). Selective doping of Mn2+ and Cr3+ has been demonstrated in the dual-phase TGCs. Benefited from the enrichment and diversity of crystalline environments, broadband/multiplexed and enhanced luminescence is achieved. The highly crystallized multi-phase TGCs inheriting both advantages of optical functional crystals and chemically inert and mechanically robust glasses, are doomed to play a key role in photonics and optoelectronics.

Heat transport through nanoscale gaps—A perspective

This perspective describes the key physical concepts at play capturing transport regimes in gaps with sizes ranging from the micrometer down to the Angström. The roles of photons, phonons, and electrons are highlighted and illustrated across several examples from the literature. Particularly, two situations for which atomistic calculations provide insights into the microscopic mechanisms at play in thermal transport across nanoscale gaps will be expounded, namely, thermal transport across silica clusters and in 2D materials. While experimental investigations are highly challenging and a vast field of opportunities remain open in this matter, several related domains of applications, such as thermophotovoltaics, thermoionics, thermal management, imaging, and 2D materials, are involved.

Graphene plasmonic devices for terahertz optoelectronics

Abstract Plasmonic excitations, consisting of collective oscillations of the electron gas in a conductive film or nanostructure coupled to electromagnetic fields, play a prominent role in photonics and optoelectronics. While traditional plasmonic systems are based on noble metals, recent work has established graphene as a uniquely suited materials platform for plasmonic science and applications due to several distinctive properties. Graphene plasmonic oscillations exhibit particularly strong sub-wavelength confinement, can be tuned dynamically through the application of a gate voltage, and span a portion of the infrared spectrum (including mid-infrared and terahertz (THz) wavelengths) that is not directly accessible with noble metals. These properties have been studied in extensive theoretical and experimental work over the past decade, and more recently various device applications are also beginning to be explored. This review article is focused on graphene plasmonic nanostructures designed to address a key outstanding challenge of modern-day optoelectronics – the limited availability of practical, high-performance THz devices. Graphene plasmons can be used as a means to enhance light–matter interactions at THz wavelengths in a highly tunable fashion, particularly through the integration of graphene resonant structures with additional nanophotonic elements. This capability is ideally suited to the development of THz optical modulators (where absorption is switched on and off by tuning the plasmonic resonance) and photodetectors (relying on plasmon-enhanced intraband absorption or rectification of charge-density waves), and promising devices based on these principles have already been reported. Novel radiation mechanisms, including light emission from electrically excited graphene plasmons, are also being explored for the development of compact narrowband THz sources.

Active metamaterial nearly perfect light absorbers: a review [Invited

Achieving nearly perfect light absorption from the microwave to optical region utilizing metamaterials has begun to play a significant role in photonics and optoelectronics due to their vital applications in thermal emitters, thermal photovoltaics, photovoltaics, sensing, filtering, and photodetection. However, employing passive components in designing perfect absorbers based on metamaterials and photonic crystals imposes some limits on their spectral operation. In order to overcome those limits, extensive research has been conducted on utilizing different materials and mechanisms to obtain active metamaterial light absorbers. In this review paper, we investigate the recent progress in tunable and reconfigurable metamaterial light absorbers through reviewing different active materials and mechanisms, and we provide a perspective for their future development and applications.

BIOPHOTONS IN RADIOBIOLOGY: INHIBITORS, COMMUNICATORS AND REACTORS.

Radiation-induced bystander effects refer to the production of signals from irradiated cells which induce responses in unirradiated, or bystander, cells. There has been a recent resurgence of interest in low-energy photon biology. This is due to concerns about health effects, increased use of biophoton imaging techniques, and the fact that biophotons can act as a bystander signal. This review discusses the history of light signaling in biology and potential mechanisms involved in the generation and transduction of signaling mechanisms. The role of photons in signaling in the animal and plant kingdoms is also reviewed. Finally, the potential to harness these mechanisms in radiation protection or therapy is discussed with emphasis on promising future directions for research.

Hybridization-induced broadband terahertz wave absorption with graphene metasurfaces

Electromagnetic (EM) wave absorption plays a vital role in photonics. While metasurfaces are proposed to absorb EM waves efficiently, most of them exhibit limited bandwidth and fixed functionalities. Here, we propose a broadband and tunable terahertz (THz) absorber based on a graphene-based metasurface, which is constructed by a single layer of closely patterned graphene concentric double rings and a metallic mirror separated by an ultrathin SiO2 layer. Plasmonic hybridization between two graphene rings significantly enlarges the absorption bandwidth, which can be further tuned by gating the graphene. Moreover, the specific design also makes our device insensitive to the incident angle and polarization state of impinging EM waves. Our results may inspire certain wave-modulation-related applications, such as THz imaging, smart absorber, tunable sensor, etc.

High-aspect-ratio microstructures with versatile slanting angles on silicon by uniform metal-assisted chemical etching

High-aspect-ratio (HAR) microstructures on silicon (Si) play key roles in photonics and electromechanical devices. However, it has been challenging to fabricate HAR microstructures with slanting profiles. Here we report successful fabrication of uniform HAR microstructures with controllable slanting angles on (1 0 0)-Si by slanted uniform metal-assisted chemical etching (SUMaCE). The trenches have width of 2 µm, aspect ratio greater than 20:1 and high geometric uniformity. The slanting angles can be adjusted between 2–70° with respect to the Si surface normal. The results support a fundamental hypothesis that under the UMaCE condition, the preferred etching direction is along the normal of the thin film catalysts, regardless of the relative orientation of the catalyst to Si substrates or the crystalline orientation of the substrates. The SUMaCE method paves the way to HAR 3D microfabrication with arbitrary slanting profiles inside Si.

The role of photonics and natural curing agents of TGF-β1 in treatment of osteoarthritis

Osteoarthritis (OA) is a degenerative disease leading to the breakdown of the hyaline cartilage between a varieties of diarthrodial joints such as the knee joint, carpals of the wrist and etc. When the cartilage is affected by trauma or wear and tear, Osteolysis may occur; broken debris of cartilage found within the synovial fluid may be recognised as a pathogen and therefore, the body’s autoimmune response will directly target the cartilage for destruction. Cytokines are proteins/peptides of glycoproteins that are secreted by cells and are involved in interaction and communication between cells. Transforming Growth Factors Beta 1 (TGF-β1) is one of well-known cytokines and had shown many effects on cellular biology including simulation or inhibition of cell proliferation, differentiation, production of extracellular matrix (ECM), remodelling, and producing both hormones and growth factors. On the other hand, Photonics recently play an important role for treatment of OA. The main aim of this review article is to investigate the effect of TGF-β1 in treatment of OA. Other important aim of this work is to explore the broad applications of optics and photonics in biomedical applications including treatment of OA. Biomedical applications of photonics have broad aspects including laser, carbon nanotubes (CNTs), quantum dots (QDs) and graphene and photodynamic therapy (PDT) which discussed in this review paper.

Theoretical study on sensitivity enhancement in energy-deficit region of chemically amplified resists used for extreme ultraviolet lithography

The role of photons in lithography is to transfer the energy and information required for resist pattern formation. In the information-deficit region, a trade-off relationship is observed between line edge roughness (LER) and sensitivity. However, the sensitivity can be increased without increasing LER in the energy-deficit region. In this study, the sensitivity enhancement limit was investigated, assuming line-and-space patterns with a half-pitch of 11 nm. LER was calculated by a Monte Carlo method. It was unrealistic to increase the sensitivity twofold while keeping the line width roughness (LWR) within 10% critical dimension (CD), whereas the twofold sensitivity enhancement with 20% CD LWR was feasible. The requirements are roughly that the sensitization distance should be less than 2 nm and that the total sensitizer concentration should be higher than 0.3 nm−3.