ORCID Profile
0000-0002-9283-6037
Current Organisations
US Forest Service
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ITMO University
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Interdisciplinary Engineering | Electrical and Electronic Engineering not elsewhere classified | Nanophotonics | Interdisciplinary Engineering not elsewhere classified |
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Publisher: IOP Publishing
Date: 18-10-2012
DOI: 10.1088/0957-4484/23/44/444006
Abstract: We study guided optical modes of a planar plasmonic waveguide filled with a generic anisotropic medium. In particular, we show that both surface and oscillatory modes exist for such waveguides and find their numbers for two specific forms of the anisotropy tensor. We also show that lossless waveguides, characterized by a diagonal permittivity tensor, support simultaneously both the forward and backward propagating modes (surface or oscillatory type) with antisymmetric field patterns. Another family of guided oscillatory modes may be supported by the waveguide if its anisotropy is created by an external magnetic field. These new modes are asymmetric in nature, exhibit extremely low effective refractive indices and may propagate over macroscopic distances without significant attenuation, while remaining strongly confined to the waveguide.
Publisher: The Optical Society
Date: 16-06-2017
DOI: 10.1364/OL.42.002423
Publisher: IOP Publishing
Date: 28-09-2022
Abstract: Benefiting from the prominent performance in high-density information storage and fast accessing of two-dimensional data, holography has attracted tremendous attentions. The wavefront recording of traditional holographic devices such as diffraction optical elements suffers from the design complexity and poor resolution as it relies on phase accumulation in the propagating mode, which is achieved by gradually varying the refractive index or thickness of the medium. Ultrathin metasurfaces made of engineered meta-atoms can overcome these limitations owing to their outstanding design flexibility and subwavelength thicknesses. In contrast to the traditional bulky holographic components, the performance of metasurfaces is determined by the electromagnetic response of the meta-atoms with spatially varying in-plane geometric parameters or rotation angles, which enables them to flexibly control the phase, litude, wavelength, and polarization of electromagnetic wave. Because of the design flexibility and the capacity of arbitrary wavefront manipulation, metasurfaces are emerging as a promising candidate for holographic memory systems. Here, we review the fast-growing field of metasurface holograms from design principles to recent advances in microwave regime. At the end of the review, we discuss potential applications of the metasurface holography and present a future research outlook.
Publisher: OSA
Date: 2010
Publisher: AIP Publishing
Date: 06-02-2023
DOI: 10.1063/5.0137042
Abstract: The unique properties of incommensurate two-dimensional bilayer structures, a wide class of optical materials, are largely determined by the relative rotation angle between the layers. Here, we present a comprehensive theoretical analysis of the optical properties of a dodecagonal quasicrystal based on twisted bilayer material with hexagonal layers rotated by 30°. By assuming that the quasicrystal is tuned to the Bragg condition, we calculate its reflectance spectra and reveal the Wood anomalies therein, which are characteristics of structures with a long-range order. It is also shown that the reflectance spectra can be dynamically controlled by the external electric field applied perpendicular to the quasicrystal's surface. This feature can be used to create tunable photonic devices such as optical switches and sharp M-shape bandpass filters.
Publisher: IOP Publishing
Date: 23-08-2021
Publisher: IEEE
Date: 08-2011
Publisher: The Optical Society
Date: 06-11-2012
DOI: 10.1364/OE.20.026275
Publisher: The Optical Society
Date: 20-03-2013
DOI: 10.1364/OL.38.001046
Publisher: American Chemical Society (ACS)
Date: 24-01-2014
DOI: 10.1021/JP411695M
Publisher: Springer Science and Business Media LLC
Date: 05-12-2016
DOI: 10.1038/S41598-016-0017-0
Abstract: The ability to induce optical activity in nanoparticles and dynamically control its strength is of great practical importance due to potential applications in various areas, including biochemistry, toxicology, and pharmaceutical science. Here we propose a new method of creating optical activity in originally achiral quantum nanostructures based on the mixing of their energy states of different parities. The mixing can be achieved by selective excitation of specific states or via perturbing all the states in a controllable fashion. We analyze the general features of the so produced optical activity and elucidate the conditions required to realize the total dissymmetry of optical response. The proposed approach is applicable to a broad variety of real systems that can be used to advance chiroptical devices and methods.
Publisher: The Optical Society
Date: 25-06-2013
DOI: 10.1364/OL.38.002259
Publisher: SPIE-Intl Soc Optical Eng
Date: 07-11-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CC45506H
Abstract: We report on the synthesis and characterization of single-crystal caged gold nanorods (CGNRs) which exhibited broadband plasmonic resonances. Redshift of plasmon resonance can be realized by increasing the length, whereas blueshift can be achieved by increasing either the overall width of the cage or the thickness of nanocage walls.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2010
Publisher: Springer Science and Business Media LLC
Date: 18-03-2016
DOI: 10.1038/SREP23321
Abstract: Since chiral nanoparticles are much smaller than the optical wavelength, their enantiomers show little difference in the interaction with circularly polarized light. This scale mismatch makes the enhancement of enantioselectivity in optical excitation of nanoobjects a fundamental challenge in modern nanophotonics. Here we demonstrate that a strong dissymmetry of optical response from achiral nanoobjects can be achieved through their arrangement into chiral superstructures with the length scale comparable to the optical wavelength. This concept is illustrated by the ex le of the simple helix supercrystal made of semiconductor quantum dots. We show that this supercrystal almost fully absorbs light with one circular polarization and does not absorb the other. The giant circular dichroism of the supercrystal comes from the formation of chiral bright excitons, which are the optically active collective excitations of the entire supercrystal. Owing to the recent advances in assembly and self-organization of nanocrystals in large superparticle structures, the proposed principle of enantioselectivity enhancement has great potential of benefiting various chiral and analytical methods, which are used in biophysics, chemistry, and pharmaceutical science.
Publisher: American Chemical Society (ACS)
Date: 26-02-2014
DOI: 10.1021/NN406015D
Abstract: Spaser is a nanoscale source of surface plasmons comprising a plasmonic resonator and gain medium to replenish energy losses. Here we propose a carbon-based spaser design in which a graphene nanoflake (GNF) resonator is coupled to a carbon nanotube (CNT) gain element. We theoretically demonstrate that the optically excited CNT can nonradiatively transfer its energy to the localized plasmon modes of the GNF because of the near-field interaction between the modes and the CNT excitons. By calculating the localized fields of the plasmon modes and the matrix elements of the plasmon-exciton interaction, we find the optimal geometric and material parameters of the spaser that yield the highest plasmon generation rate. The results obtained may prove useful in designing robust and ultracompact coherent sources of surface plasmons for plasmonic nanocircuits.
Publisher: The Optical Society
Date: 08-08-2011
DOI: 10.1364/OE.19.016058
Publisher: The Optical Society
Date: 30-11-2015
DOI: 10.1364/OE.24.000A52
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 02-2013
Publisher: The Optical Society
Date: 17-05-2016
DOI: 10.1364/OL.41.002438
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2017
Publisher: SPIE
Date: 02-05-2014
DOI: 10.1117/12.2051755
Publisher: American Chemical Society (ACS)
Date: 18-09-2020
Publisher: American Chemical Society (ACS)
Date: 06-02-2015
DOI: 10.1021/NL504369X
Abstract: Optical activity is a common natural phenomenon, which occurs in in idual molecules, biomolecules, biological species, crystalline solids, liquid crystals, and various nanosized objects, leading to numerous important applications in almost every field of modern science and technology. Because this activity can hardly be altered, creation of artificial active media with controllable optical properties is of paramount importance. Here, for the first time to the best of our knowledge, we theoretically demonstrate that optical activity can be inherent to many semiconductor nanowires, as it is induced by chiral dislocations naturally developing during their growth. By assembling such nanowires in two- or three-dimensional periodic lattices, one can create optically active quantum supercrystals whose activity can be varied in many ways owing to the size quantization of the nanowires' energy spectra. We believe that this research is of particular importance for the future development of semiconducting nanomaterials and their applications in nanotechnology, chemistry, biology, and medicine.
Publisher: American Chemical Society (ACS)
Date: 14-08-2014
DOI: 10.1021/NN503745U
Abstract: This work presents a comprehensive study of electroabsorption in CdSe colloidal quantum dots, nanorods, and nanoplatelets. We experimentally demonstrate that the exposure of the nanoplatelets to a dc electric field leads to strong broadening of their lowest-energy heavy-hole absorption band and drastically reduces the absorption efficiency within the band. These are results of the quantum-confined Stark and Franz–Keldysh effects. The field-induced change in the nanoplatelets’ absorption is found to be more than 10 times the change in the absorption by the quantum dots. We also demonstrate that the electroabsorption by the nanorods is weaker than that by the quantum dots and nanoplatelets and reveal an unusual dependence of the differential absorption changes on the nanoplatelet thickness: the thicker the nanoplatelet, the smaller the change.
Publisher: IEEE
Date: 12-2009
Publisher: Informa UK Limited
Date: 08-12-2019
Publisher: The Optical Society
Date: 16-02-2018
DOI: 10.1364/OE.26.005052
Publisher: AIP
Date: 2010
DOI: 10.1063/1.3506140
Publisher: American Chemical Society (ACS)
Date: 23-12-2019
Publisher: Walter de Gruyter GmbH
Date: 09-2016
Abstract: Controlling the strength of enantioselective interaction of chiral inorganic nanoparticles with circularly polarized light is an intrinsically interesting subject of contemporary nanophotonics. This interaction is relatively weak, because the chirality scale of nanoparticles is much smaller than the optical wavelength. Here we theoretically demonstrate that ion doping provides a powerful tool of engineering and enhances optical activity of semiconductor nanocrystals. We show that by carefully positioning ionic impurities inside the nanocrystals, one can maximize the rotatory strengths of intraband optical transitions, and make them 100 times larger than the typical rotatory strengths of small chiral molecules.
Publisher: Pleiades Publishing Ltd
Date: 07-2006
Publisher: The Optical Society
Date: 11-2013
Publisher: IEEE
Date: 06-2014
Publisher: American Physical Society (APS)
Date: 28-03-2011
Publisher: IEEE
Date: 06-2014
Publisher: Springer Science and Business Media LLC
Date: 27-02-2014
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 15-05-2021
Publisher: The Optical Society
Date: 22-12-2010
DOI: 10.1364/OE.19.000206
Publisher: Springer Science and Business Media LLC
Date: 05-04-2017
DOI: 10.1038/SREP45925
Abstract: The studying of how twisted light interacts with chiral matter on the nanoscale is paramount for tackling the challenging task of optomechanical separation of nanoparticle enantiomers, whose solution can revolutionize the entire pharmaceutical industry. Here we calculate optical forces and torques exerted on chiral nanoparticles by Laguerre–Gaussian beams carrying a topological charge. We show that regardless of the beam polarization, the nanoparticles are exposed to both chiral and achiral forces with nonzero reactive and dissipative components. Longitudinally polarized beams are found to produce chirality densities that can be 10 9 times higher than those of transversely polarized beams and that are comparable to the chirality densities of beams polarized circularly. Our results and analytical expressions prove useful in designing new strategies for mechanical separation of chiral nanoobjects with the help of highly focussed beams.
Publisher: The Optical Society
Date: 28-09-2011
DOI: 10.1364/OE.19.019973
Publisher: AIP Publishing
Date: 10-2015
DOI: 10.1063/1.4934595
Abstract: Doped semiconductor nanocrystals is a versatile material base for contemporary photonics and optoelectronics devices. Here, for the first time to the best of our knowledge, we theoretically calculate the radiative decay rates of the lowest-energy states of donor impurity in spherical nanocrystals made of four widely used semiconductors: ZnS, CdSe, Ge, and GaAs. The decay rates were shown to vary significantly with the nanocrystal radius, increasing by almost three orders of magnitude when the radius is reduced from 15 to 5 nm. Our results suggest that spontaneous emission may dominate the decay of impurity states at low temperatures, and should be taken into account in the design of advanced materials and devices based on doped semiconductor nanocrystals.
Publisher: Hindawi Limited
Date: 2015
DOI: 10.1155/2015/982325
Publisher: IOP Publishing
Date: 12-11-2019
Publisher: American Chemical Society (ACS)
Date: 12-10-2022
Publisher: Pleiades Publishing Ltd
Date: 08-2006
Publisher: The Optical Society
Date: 23-09-2010
DOI: 10.1364/OE.18.021427
Publisher: SPIE
Date: 20-11-2012
DOI: 10.1117/12.2000630
Publisher: American Chemical Society (ACS)
Date: 28-12-2011
DOI: 10.1021/NN204498J
Abstract: The self-assembly of monodisperse inorganic nanoparticles into highly ordered arrays (superlattices) represents an exciting route to materials and devices with new functions. It allows programming their properties by varying the size, shape, and composition of the nanoparticles, as well as the packing order of the assemblies. While substantial progress has been achieved in the fabrication of superlattice materials made of nanospheres, limited advances have been made in growing similar materials with anisotropic building blocks, which is particularly true for free-standing two-dimensional superlattices. In this paper, we report the controlled growth of free-standing, large-area, monolayered gold-nanorod superlattice sheets by polymer ligands in an entropy-driven interfacial self-assembly process. Furthermore, we experimentally characterize the plasmonic properties of horizontally aligned sheets (H-sheets) and vertically aligned sheets (V-sheets) and show that observed features can be well described using a theoretical model based on the discrete-dipole approximation. Our polymer-ligand-based strategy may be extended to other anisotropic plasmonic building blocks, offering a robust and inexpensive avenue to plasmonic nanosheets for various applications in nanophotonic devices and sensors.
Publisher: American Chemical Society (ACS)
Date: 23-01-2018
Abstract: Two-dimensional (2D) nanomaterials have been intensively investigated due to their interesting properties and range of potential applications. Although most research has focused on graphene, atomic layered transition metal dichalcogenides (TMDs) and particularly MoS
Publisher: American Chemical Society (ACS)
Date: 14-07-2017
Abstract: Large surface-to-volume ratio, one-dimensional quantum confinement, and strong optical activity make chiral nanoscrolls ideal for the detection and sensing of small chiral molecules. Here, we present a simple physical model of chiroptical phenomena in multilayered tapered semiconductor nanoscrolls. Our model is based on a linear transformation of coordinates, which converts nanoscrolls into flat but topologically distorted nanoplatelets whose optical properties can then be treated analytically. As an illustrative application ex le, we analyze absorption and circular dichroism spectra of CdSe nanoscrolls using an eight-band model of CdSe. We show that the optical activity of the nanoscrolls originates from the chiral distortion of their crystal lattice and determine selection rules for the optically active interband transitions. The results of our study may prove useful for the modeling and design of semiconductor nanoscrolls and nanoscroll-based materials.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8CP04724C
Abstract: The paper presents a first theory of Frenkel excitons in two-dimensional lead halide perovskite quantum-dot supercrystals.
Publisher: Springer Science and Business Media LLC
Date: 10-2015
DOI: 10.1038/SREP14712
Abstract: For centuries mankind has been modifying the optical properties of materials: first, by elaborating the geometry and composition of structures made of materials found in nature, later by structuring the existing materials at a scale smaller than the operating wavelength. Here we suggest an original approach to introduce optical activity in nanostructured materials, by theoretically demonstrating that conventional achiral semiconducting nanocrystals become optically active in the presence of screw dislocations, which can naturally develop during the nanocrystal growth. We show the new properties to emerge due to the dislocation-induced distortion of the crystal lattice and the associated alteration of the nanocrystal’s electronic subsystem, which essentially modifies its interaction with external optical fields. The g-factors of intraband transitions in our nanocrystals are found comparable with dissymmetry factors of chiral plasmonic complexes and exceeding the typical g-factors of chiral molecules by a factor of 1000. Optically active semiconducting nanocrystals—with chiral properties controllable by the nanocrystal dimensions, morphology, composition and blending ratio—will greatly benefit chemistry, biology and medicine by advancing enantiomeric recognition, sensing and resolution of chiral molecules.
Publisher: SPIE
Date: 20-11-2012
DOI: 10.1117/12.2000637
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 03-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2012
Publisher: Optica Publishing Group
Date: 24-12-2009
DOI: 10.1364/OL.35.000055
Publisher: Wiley
Date: 13-05-2021
Abstract: Mesoscopic photonic systems with tailored optical responses have great potential to open new frontiers in implantable biomedical devices. However, biocompatibility is typically a problem, as engineering of optical properties often calls for using toxic compounds and chemicals, unsuitable for in vivo applications. Here, a unique approach to biofriendly delivery of optical resonances is demonstrated. It is shown that the controllable infusion of gold nanoseeds into polycrystalline sub‐micrometer vaterite spherulites gives rise to a variety of electric and magnetic Mie resonances, producing a tuneable mesoscopic optical metamaterial. The 3D reconstruction of the spherulites demonstrates the capability of controllable gold loading with volumetric filling factors exceeding 28%. Owing to the biocompatibility of the constitutive elements, “golden vaterite” paves the way to introduce designer‐made Mie resonances to cutting‐edge biophotonic applications. This concept is exemplified by showing efficient laser heating of gold‐filled vaterite spherulites at red and near‐infrared wavelengths, highly desirable in photothermal therapy, and photoacoustic tomography.
Publisher: Elsevier BV
Date: 11-2001
Publisher: The Optical Society
Date: 28-11-2012
DOI: 10.1364/OE.20.027612
Publisher: American Chemical Society (ACS)
Date: 06-09-2020
Publisher: Elsevier BV
Date: 11-2003
Publisher: The Optical Society
Date: 17-12-2010
DOI: 10.1364/OE.18.027916
Publisher: Springer Science and Business Media LLC
Date: 14-10-2015
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2010
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2009
Publisher: AIP Publishing
Date: 16-05-2016
DOI: 10.1063/1.4948966
Abstract: We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ by a factor of 105. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an ex le of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.
Publisher: American Chemical Society (ACS)
Date: 16-05-2018
DOI: 10.1021/ACS.JPCLETT.8B01334
Abstract: We present rigorous analysis of optical activity of chiral semiconductor gammadions whose chirality in three dimensions is caused by the nonuniformity of thickness in the transverse plane. It is shown that such gammadions not only distinguish between the two circular polarizations upon scattering and reflection of light, like all two-dimensional semiconductor nanostructures with planar chirality do, but also exhibit circular dichroism and circularly polarized luminescence. Chiral semiconductor gammadions whose charge carriers are mostly confined to the arms are found to feature both high dissymmetry of optical response and a constant-sign circular dichroism signal over a wide frequency range. It is also shown that the strength of the gammadion's chiroptical response is determined solely by two geometric factors: the variation range of the gammadion's thickness and the arms' curvature. Our seminal theoretical study is intended to lay the foundation for future applications of semiconductor gammadions in chiral nanophotonics and nanotechnology.
Publisher: American Chemical Society (ACS)
Date: 08-08-2019
DOI: 10.1021/ACS.JPCLETT.9B01724
Abstract: The availability of carbon dots (CDots) with bright red photoluminescence (PL) would significantly broaden the range of their biological and optoelectronic applications. We present a theoretical model that predicts that amino functionalization of CDots not only shifts their PL to longer wavelengths but also preserves large oscillator strengths of the fundamental radiative transitions of CDots. The model considers the optical response of amino-functionalized CDots determined by molecule-like subunits of polycyclic aromatic hydrocarbons with one, two, or three -NH
Publisher: The Optical Society
Date: 11-2015
Publisher: The Optical Society
Date: 07-11-2013
Publisher: Informa UK Limited
Date: 14-06-2023
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 08-2009
Publisher: The Optical Society
Date: 06-09-2012
Publisher: The Optical Society
Date: 10-12-2012
DOI: 10.1364/OL.37.005151
Publisher: AIP Publishing
Date: 31-10-2022
DOI: 10.1063/5.0128110
Abstract: Various methods for controlling the in-plane propagation direction and topological transitions of phonon polaritons (PhPs) in anisotropic van der Waals (vdW) materials rely on using twisted vdW bi-layers or the hybridization of anisotropic vdW materials with other functional materials such as graphene, hBN, and SiC. At the same time, visibly transparent SiC- and SiO2-based metastructures have potential to solve the problem of daytime radiative cooling. Here, as a unique method, we design a bifunctional α-MoO3-integrated SiC metasurface for effectively controlling the in-plane propagation direction of α-MoO3 PhPs. The control is enabled by a topological transition in the PhP dispersion, which is achieved by proper arrangements of the SiC meta-atoms. The proposed functionality of the designed metasurface is beneficial for the mid-infrared in-plane coupling between quantum emitters and heat management. Moreover, the α-MoO3–SiC metasurface functions as an efficient visibly transparent daytime radiative cooler.
Publisher: American Chemical Society (ACS)
Date: 29-05-2018
Abstract: 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.
Publisher: American Chemical Society (ACS)
Date: 14-08-2019
Abstract: Carbon dots (CDots) are a promising biocompatible nanoscale source of light, yet the origin of their emission remains under debate. Here, we show that all the distinctive optical properties of CDots, including the giant Stokes shift of photoluminescence and the strong dependence of emission color on excitation wavelength, can be explained by the linear optical response of the partially sp
Publisher: Pan Stanford Publishing Pte. Ltd.
Date: 08-08-2016
Publisher: American Physical Society (APS)
Date: 24-07-2007
Publisher: American Physical Society (APS)
Date: 20-09-2011
Publisher: Optica Publishing Group
Date: 30-10-2009
DOI: 10.1364/OE.17.020878
Publisher: IOP Publishing
Date: 18-10-2013
Publisher: AIP Publishing
Date: 16-07-2012
DOI: 10.1063/1.4737643
Abstract: The concept of light lification in a system of zero-index metamaterial with gain inserts is studied. We demonstrate that the radiation from a point source embedded in the system can be effectively lified and the net gain is independent of the positions of gain inserts and the source. We further investigate how the net gain grows with the imaginary part of the inserts’ permittivities and find that it saturates when the imaginary part is sufficiently large. It is also shown that the efficiency of lification is significantly reduced when lossy inserts are introduced into the system.
Publisher: The Optical Society
Date: 10-03-2014
DOI: 10.1364/OE.22.006229
Publisher: The Optical Society
Date: 14-12-2010
DOI: 10.1364/OL.35.004190
Publisher: OSA
Date: 2014
Publisher: The Optical Society
Date: 11-2015
Publisher: IEEE
Date: 08-2011
Publisher: American Chemical Society (ACS)
Date: 04-08-2017
DOI: 10.1021/ACS.NANOLETT.7B02203
Abstract: Engineering nanostructured optical materials via the purposeful distortion of their constituent nanocrystals requires the knowledge of how various distortions affect the nanocrystals' 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.
Publisher: American Chemical Society (ACS)
Date: 21-09-2012
DOI: 10.1021/NN3029106
Abstract: We report on an anomalous size dependence of the room-temperature photoluminescence decay time from the lowest-energy state of PbS quantum dots in colloidal solution, which was found using the transient luminescence spectroscopy. The observed 10-fold reduction in the decay time (from ~2.5 to 0.25 μs) with the increase in the quantum dots' diameter is explained by the existence of phonon-induced transitions between the in-gap state-whose energy drastically depends on the diameter-and the fundamental state of the quantum dots.
Publisher: IEEE
Date: 04-2010
Publisher: MDPI AG
Date: 14-02-2020
Abstract: Analytical modeling of soft pneumatic actuators constitutes a powerful tool for the systematic design and characterization of these key components of soft robotics. Here, we maximize the quasi-static bending angle of a soft pneumatic actuator by optimizing its cross-section for a fixed positive pressure inside it. We begin by formulating a general theoretical framework for the analytical calculation of the bending angle of pneumatic actuators with arbitrary cross-sections, which is then applied to an actuator made of a circular polymer tube and an asymmetric patch in the shape of a hollow-cylinder sector on its outer surface. It is shown that the maximal bending angle of this actuator can be achieved using a wide range of patches with different optimal dimensions and approximately the same cross-sectional area, which decreases with pressure. We also calculate the optimal dimensions of thin and small patches in thin pneumatic actuators. Our analytical results lead to clear design guidelines, which may prove useful for engineering and optimization of the key components of soft robotics with superior features.
Publisher: The Optical Society
Date: 02-03-2017
DOI: 10.1364/OE.25.005781
Publisher: American Chemical Society (ACS)
Date: 05-01-2018
Publisher: OSA
Date: 2013
Publisher: IEEE
Date: 08-2011
Publisher: Hindawi Limited
Date: 2011
DOI: 10.1155/2011/581810
Abstract: We theoretically study the problem of Raman gain maximization in uniform silicon photonic-crystal waveguides supporting slow optical modes. For the first time, an exact solution to this problem is obtained within the framework of the undepleted-pump approximation. Specifically, we derive analytical expressions for the maximum signal gain, optimal input pump power, and optimal length of a silicon Raman lifier and demonstrate that the ultimate gain is achieved when the pump beam propagates at its maximum speed. If the signal’s group velocity can be reduced by a factor of 10 compared to its value in a bulk silicon, it may result in ultrahigh gains exceeding 100 dB. We also optimize the device parameters of a silicon Raman lifier in the regime of strong pump depletion and come up with general design guidelines that can be used in practice.
Publisher: The Optical Society
Date: 11-07-2013
Publisher: SPIE
Date: 20-11-2012
DOI: 10.1117/12.2001073
Publisher: The Optical Society
Date: 08-08-2014
DOI: 10.1364/OE.22.019707
Publisher: SPIE
Date: 20-02-2017
DOI: 10.1117/12.2256985
Publisher: AIP Publishing
Date: 25-03-2013
DOI: 10.1063/1.4799281
Abstract: We present an effective method for actively controlling intrinsic resonances of optical metamaterials using graphene. Exploiting the Fermi level shift and associated variations in optical transitions of graphene due to voltage biasing, we attain the ability to significantly modulate the intrinsic resonance of the fishnet structure. Despite being atomically thin and having a weak optical response, graphene can be strongly coupled with the left-handed resonance of the fishnet metamaterial. We unambiguously demonstrate that the resonant transmission, absorption, and effective constitutive parameters of the graphene-coupled fishnet metamaterial can be precisely controlled by varying the bias voltage.
Publisher: Pleiades Publishing Ltd
Date: 05-2006
Publisher: Optica Publishing Group
Date: 26-03-2009
DOI: 10.1364/OE.17.005807
Abstract: We present a novel method for maximizing signal gain in continuously pumped silicon-waveguide Raman lifiers made with silicon-on-insulator technology. Our method allows for pump-power depletion during Raman lification and makes use of a variational technique. Its use leads to a system of four coupled nonlinear differential equations, whose numerical solution provides the optimal axial profile of the effective mode area along the waveguide length that maximizes the output signal power for a given lifier length and a preset input (or output) cross-section area. In practice, the optimum profile can be realized by varying the cross-section area of a silicon waveguide along its length by tapering its width appropriately.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 09-2010
Publisher: American Physical Society (APS)
Date: 30-01-2008
Publisher: The Optical Society
Date: 08-06-2012
DOI: 10.1364/OL.37.002295
Publisher: Optica Publishing Group
Date: 13-02-2009
DOI: 10.1364/OL.34.000536
Abstract: We present approximate analytical expressions describing nonlinear interaction of two optical waves copropagating inside a silicon waveguide in the presence of linear losses, stimulated Raman scattering, and free-carrier absorption. Our approach avoids the undepleted-pump approximation, which we show to be inadequate to describe accurately the Raman-gain process. Based on our calculations, we propose a new generalized definition for the effective length and show that it provides better insight into the impact of nonlinear absorption on Raman lification in silicon waveguides.
Publisher: The Optical Society
Date: 28-07-2011
DOI: 10.1364/OE.19.015459
Publisher: AIP Publishing
Date: 05-01-2015
DOI: 10.1063/1.4905258
Abstract: The coherent coupling of quantum dots is a sensitive indicator of the energy and phase relaxation processes taking place in the nanostructure components. We formulate a theory of low-temperature, stationary photoluminescence from a quantum-dot molecule composed of two spherical quantum dots whose electronic subsystems are resonantly coupled via the Coulomb interaction. We show that the coupling leads to the hybridization of the first excited states of the quantum dots, manifesting itself as a pair of photoluminescence peaks with intensities and spectral positions strongly dependent on the geometric, material, and relaxation parameters of the quantum-dot molecule. These parameters are explicitly contained in the analytical expression for the photoluminescence differential cross section derived in the paper. The developed theory and expression obtained are essential in interpreting and analyzing spectroscopic data on the secondary emission of coherently coupled quantum systems.
Publisher: SPIE
Date: 13-09-2013
DOI: 10.1117/12.2023025
Publisher: Springer Science and Business Media LLC
Date: 05-11-2014
DOI: 10.1038/SREP06917
Publisher: MDPI AG
Date: 12-05-2020
DOI: 10.3390/NANO10050933
Abstract: This paper presents the first general theory of electronic band structure and intersubband transitions in three-layer semiconductor nanoplatelets. We find a dispersion relation and wave functions of the confined electrons and use them to analyze the band structure of core/shell nanoplatelets with equal thicknesses of the shell layers. It is shown that the energies of electrons localized inside the shell layers can be degenerate for certain electron wave vectors and certain core and shell thicknesses. We also show that the energies of intersubband transitions can be nonmonotonic functions of the core and shell thicknesses, exhibiting pronounced local minima and maxima which can be observed in the infrared absorption spectra. Our results will prove useful for the design of photonic devices based on multilayered semiconductor nanoplatelets operating at infrared frequencies.
Publisher: Optica Publishing Group
Date: 06-11-2009
DOI: 10.1364/OE.17.021179
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2012
Publisher: The Optical Society
Date: 23-08-2011
DOI: 10.1364/OL.36.003374
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2011
Publisher: Wiley
Date: 18-10-2020
DOI: 10.1002/JBM.B.34739
Abstract: There is a growing demand for polymer fiber scaffolds for biomedical applications and tissue engineering. Biodegradable polymers such as polycaprolactone have attracted particular attention due to their applicability to tissue engineering and optical neural interfacing. Here we report on a scalable and inexpensive fiber fabrication technique, which enables the drawing of PCL fibers in a single process without the use of auxiliary cladding. We demonstrate the possibility of drawing PCL fibers of different geometries and cross-sections, including solid-core, hollow-core, and grooved fibers. The solid-core fibers of different geometries are shown to support cell growth, through successful MCF-7 breast cancer cell attachment and proliferation. We also show that the hollow-core fibers exhibit a relatively stable optical propagation loss after submersion into a biological fluid for up to 21 days with potential to be used as waveguides in optical neural interfacing. The capacity to tailor the surface morphology of biodegradable PCL fibers and their non-cytotoxicity make the proposed approach an attractive platform for biomedical applications and tissue engineering.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2010
Publisher: IOP Publishing
Date: 03-2013
Publisher: The Optical Society
Date: 13-02-2017
DOI: 10.1364/OE.25.003811
Publisher: The Optical Society
Date: 05-12-2012
DOI: 10.1364/BOE.4.000015
Publisher: Optica Publishing Group
Date: 24-06-2010
DOI: 10.1364/OL.35.002221
Publisher: The Optical Society
Date: 05-07-2010
DOI: 10.1364/OL.35.002343
Publisher: American Physical Society (APS)
Date: 09-05-2005
Publisher: SPIE
Date: 10-02-2011
DOI: 10.1117/12.873651
Publisher: SPIE
Date: 13-09-2013
DOI: 10.1117/12.2023237
Publisher: SPIE
Date: 13-09-2013
DOI: 10.1117/12.2023633
Publisher: The Optical Society
Date: 06-09-2011
Publisher: Optica Publishing Group
Date: 11-03-2010
DOI: 10.1364/OE.18.006191
Publisher: Wiley
Date: 21-02-2017
Publisher: American Chemical Society (ACS)
Date: 09-01-2019
Publisher: American Chemical Society (ACS)
Date: 21-01-2016
Publisher: Pleiades Publishing Ltd
Date: 2017
Publisher: Elsevier BV
Date: 03-2023
Publisher: The Optical Society
Date: 31-10-2011
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2009
Publisher: Springer Science and Business Media LLC
Date: 10-02-2020
Publisher: American Chemical Society (ACS)
Date: 11-06-2019
Publisher: Wiley
Date: 18-06-2003
Publisher: Pleiades Publishing Ltd
Date: 2017
Publisher: AIP Publishing
Date: 17-06-2013
DOI: 10.1063/1.4812200
Abstract: We theoretically demonstrate an advanced optical modulator based on graphene-enabled metamaterial with voltage-controllable reflectance. A significant modulation depth of the reflection coefficient is achieved through a voltage biasing of the graphene's Fermi level, leading to an almost instantaneous change in the effective permittivity of the graphene. We show that even a single graphene layer integrated into the structure of a simple metamaterial absorber enables a relative change in the reflectance as high as 361% at near-infrared frequencies. The designed modulator may be used in optical communication systems and biomedical sensing apparatus.
Publisher: Hindawi Limited
Date: 10-12-2012
DOI: 10.1155/2012/514270
Publisher: Pleiades Publishing Ltd
Date: 09-2012
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2014
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 06-2012
Publisher: The Optical Society
Date: 29-01-2013
DOI: 10.1364/OE.21.002832
Publisher: The Optical Society
Date: 06-03-2012
DOI: 10.1364/OE.20.006616
Publisher: SPIE
Date: 13-09-2013
DOI: 10.1117/12.2023801
Publisher: AIP Publishing
Date: 08-04-2014
DOI: 10.1063/1.4870862
Abstract: Despite chiral metamaterials being widely appreciated for their giant optical activity and negative refractive index with respect to the transmitted electromagnetic waves, little research efforts are devoted to effects occurring upon optical reflection from such metamaterials. Here, we theoretically demonstrate highly energy-efficient cross-polarization conversion for a normally incident wave reflecting from metamaterial with a broken four-fold symmetry of chiral structure. We do this by designing metamaterial that makes the polarization plane of a linearly polarized electromagnetic wave reflected from its surface almost perpendicular to the polarization plane of the incident wave. Using reflection from this metamaterial, one can also freely convert between left-handed and right-handed circular polarizations without significant energy loss. The proposed chiral metamaterial may prove useful in electromagnetic communication systems, polarization controllable antennas, and on-chip biomedical sensors.
Publisher: IOP Publishing
Date: 11-12-2013
Publisher: Springer Science and Business Media LLC
Date: 25-04-2013
DOI: 10.1038/SREP01727
Abstract: The study of supercrystals made of periodically arranged semiconductor quantum dots is essential for the advancement of emerging nanophotonics technologies. By combining the strong spatial confinement of elementary excitations inside quantum dots and exceptional design flexibility, quantum-dot supercrystals provide broad opportunities for engineering desired optical responses and developing superior light manipulation techniques on the nanoscale. Here we suggest tailoring the energy spectrum and wave functions of the supercrystals' collective excitations through the variation of different structural and material parameters. In particular, by calculating the excitonic spectra of quantum dots assembled in two-dimensional Bravais lattices we demonstrate a wide variety of spectrum transformation scenarios upon alterations in the quantum dot arrangement. This feature offers unprecedented control over the supercrystal's electromagnetic properties and enables the development of new nanophotonics materials and devices.
Publisher: Optica Publishing Group
Date: 16-09-2009
DOI: 10.1364/OE.17.017570
Publisher: Hindawi Limited
Date: 08-2012
DOI: 10.1155/2012/907183
Abstract: Most metamaterials exhibit pronounced anisotropic properties that are crucial for the understanding of their superior optical behavior, especially when they are integrated into the structure of a plasmonic waveguide. In this paper, we analytically solve the dispersion relation for a slot plasmonic waveguide filled with an anisotropic-stratified metamaterial and reveal that it supports two modes featuring relatively long propagation lengths in the limit of vanishing slot thickness. We classify these modes according to their physical origin and study the variation of their dispersion properties with material parameters.
Publisher: American Chemical Society (ACS)
Date: 29-08-2016
Abstract: Here we report anisotropy of intrinsic chiroptical response in CdSe/CdS quantum dot-in-rod systems. These nanostructures being oriented in an external electric field demonstrate dependence of circular dichroism signal on the orientation of the nanocrystals. The type of circular polarization in these nanostructures correlates with preferential direction of linear polarization, and the degree of circular polarization is the maximal for the first circular dichroism band corresponding to the absorption band edge. We also support our experimental data with a theoretical model. Using this model, we show a direct connection between theoretically derived morphological parameters of twisting in nanocrystals lattices and calculated from experimental data parameters of circular dichroism anisotropy.
Publisher: Optica Publishing Group
Date: 18-11-2009
DOI: 10.1364/OE.17.022124
Publisher: IOP Publishing
Date: 06-2023
Abstract: Even when fabricated under ideal conditions twisted bilayer graphene (TBG) inevitably contains various defects which may significantly affect its physical properties. Here we comprehensively analyze the impact of typical point defects, represented by adsorbed hydrogen atoms, on the electronic and optical properties of TBG. It is shown using self-consistent tight-binding Hamiltonians that such point defects make TBG ferromagnetic, and that its ground state comprises a pair of nearly dispersionless spin-polarized energy bands around the Fermi level. Transitions to and from these bands strongly modify the infrared absorption of TBG and result in a sharp low-energy peak in its spectrum. It is also revealed that the adsorption of hydrogen atoms suppresses the circular dichroism of TBG due to the weakening of the electronic coupling between the graphene layers. Our findings will guide future experimental studies on the optical properties of TBG in realistic, impurity-rich environments.
Publisher: The Optical Society
Date: 26-06-2017
DOI: 10.1364/OE.25.015737
Publisher: American Chemical Society (ACS)
Date: 04-05-2023
Publisher: The Optical Society
Date: 06-03-2012
Publisher: Pleiades Publishing Ltd
Date: 2017
Publisher: AIP Publishing
Date: 07-01-2013
DOI: 10.1063/1.4774320
Abstract: Although zero-index metamaterials (ZIMs) have been extensively studied in electromagnetics, their applications in plasmonics have not been investigated so far. In this Letter, we propose strategies for efficient manipulation of surface plasmon polariton (SPP) flow using anisotropic ZIMs. Through rigorous theoretical analysis backed up by full-wave simulations, we suggest two applications of anisotropic ZIMs in plasmonics, namely, adjusting the phase delay of SPPs and guiding SPPs about a rounded metal corner. The proposed applications of ZIMs may prove useful for plasmonic interconnects in integrated ultra-high speed circuitry.
Publisher: Springer Science and Business Media LLC
Date: 17-06-2014
Publisher: The Optical Society
Date: 19-06-2013
DOI: 10.1364/OE.21.015335
Publisher: AIP Publishing
Date: 14-03-2022
DOI: 10.1063/5.0083817
Abstract: Black phosphorous (BP) is a well-known two-dimensional van der Waals (vdW) material with in-plane anisotropy and remarkable electronic and optical properties. Here, we comprehensively analyze the near-field radiative heat transfer (NFRHT) between a pair of parallel non-rotated BP flakes that occurs due to the tunneling of the coupled anisotropic surface plasmon polaritons (SPPs) supported by the flakes. It is demonstrated that the covering of the BP flakes with hexagonal boron nitride (hBN) films leads to the hybridization of the BP's SPPs with the hBN's hyperbolic phonon polaritons and to the significant enhancement of the NFRHT at the hBN's epsilon-near-zero frequencies. It is also shown that the NFRHT in the BP/hBN parallel-plate structure can be actively switched between the ON and OFF states by changing the chemical potential of the BPs and that the NFRHT can be modified by altering the number of the BP layers. Finally, we replace hBN with α-MoO3 and explore how the NFRHT is spectrally and strongly modified in the BP/α-MoO3 parallel-plate structure. We believe that the proposed BP olar-vdW-material parallel-plate structures can prove useful in the thermal management of optoelectronic devices.
Publisher: IEEE
Date: 07-2012
Publisher: Springer Science and Business Media LLC
Date: 09-11-2016
DOI: 10.1038/SREP36884
Abstract: Fast and reliable separation of enantiomers of chiral nanoparticles requires elimination of all the forces that are independent of the nanoparticle handedness and creation of a sufficiently strong force that either pushes different enantiomers in opposite directions or delays the diffusion of one of them with respect to the other. Here we show how to construct such a completely chiral optical force using two counterpropagating circularly polarized plane waves of opposite helicities. We then explore capabilities of the related enantioseparation method by analytically solving the problem of the force-induced diffusion of chiral nanoparticles in a confined region, and reveal that it results in exponential spatial dependencies of the quantities measuring the purity of chiral substances. The proposed concept of a completely chiral optical force can potentially advance enantioseparation and enantiopurification techniques for all kinds of chiral nanoparticles that strongly interact with light.
Publisher: AIP Publishing
Date: 21-11-2022
DOI: 10.1063/5.0134300
Publisher: The Optical Society
Date: 15-09-2010
DOI: 10.1364/OL.35.003138
Publisher: Walter de Gruyter GmbH
Date: 06-2020
Abstract: Mid-infrared (MIR) plasmon-phonon features of heterostructures composing of a plasmonic anisotropic two-dimensional material (A2DM) on a hexagonal boron nitride (hBN) film are analyzed. We derive the exact dispersion relations of plasmon-phonons supported by the heterostructures and demonstrate the possibility of topological transitions of these modes within the second Reststrahlen band of hBN. The topological transitions lead to enhanced local density of plasmon-phonon states, which intensifies the spontaneous emission rate, if the thickness of the hBN layer is appropriately chosen. We also investigate a lateral junction formed by A2DM/hBN and A2DM, demonstrating that one can realize asymmetric guiding, beaming, and unidirectionality of the hybrid guided modes. Our findings demonstrate potential capabilities of the A2DM/hBN heterostructures for active tunable light–matter interactions and asymmetric in-plane polariton nanophotonics in the MIR range.
Publisher: Pleiades Publishing Ltd
Date: 09-2012
Publisher: The Optical Society
Date: 12-08-2010
DOI: 10.1364/OE.18.018324
Publisher: Springer Science and Business Media LLC
Date: 28-03-2013
Abstract: We theoretically study the properties of the optimal size distribution in the ensemble of hollow gold nanoshells (HGNs) that exhibits the best performance at in vivo biomedical applications. For the first time, to the best of our knowledge, we analyze the dependence of the optimal geometric means of the nanoshells’ thicknesses and core radii on the excitation wavelength and the type of human tissue, while assuming lognormal fit to the size distribution in a real HGN ensemble. Regardless of the tissue type, short-wavelength, near-infrared lasers are found to be the most effective in both absorption- and scattering-based applications. We derive approximate analytical expressions enabling one to readily estimate the parameters of optimal distribution for which an HGN ensemble exhibits the maximum efficiency of absorption or scattering inside a human tissue irradiated by a near-infrared laser.
Location: United Kingdom of Great Britain and Northern Ireland
Location: Russian Federation
Start Date: 03-2012
End Date: 04-2016
Amount: $375,000.00
Funder: Australian Research Council
View Funded Activity