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We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of “transition absorption”, i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate photoemission rate and transition absorption for nanoparticles surrounded by various media with a broad range of permittivities and show that photoemission rate and transition absorption follow the same dependence on the permittivity. Thus, we conclude that transition absorption is responsible for the enhancement of photoemission in the surface scenario. We calculate the ratio of photoemission cross-section for a gold nanosphere embedded in different materials such as silicon, zinc oxide, and titanium dioxide. For the calculations, we include both surface and bulk mechanisms of photoemission, using quantum calculations for the former one and a three-step phenomenological approach for the latter one. By comparison of both m...

Recently it has been shown that plasmonic effects in hyperbolic metamaterials may facilitate overcoming the diffraction limit and enhance the contrast function of an image by filtering background radiation. Unfortunately, the contrast function of such a dark‐field hyperlens degrades in the deep‐subwavelength regime. We push forward the concept of the contrast function revival in the subwavelength imaging by introduction of the proper phase difference between coherent sources. To study this effect we develop a simplified theory of the wave propagation through a hyperbolic metamaterial and show that, in principle, two sources standing apart at any subwavelength distance can be distinguished. We suggest two feasible designs, the first of which employs the obliquely incident light, while the second one is based on a properly designed metasurface. The concept can be used in high‐contrast subwavelength microscopy.

The method to achieve a high resolution of subwavelength features (to improve the contrast function) for a dark-field hyperlens — hyperbolic metamaterial slab possessing metallic properties at the interface — is developed. The technique requires the introduction of the phase difference between the objects to be resolved to have a destructive interference between the individual transmitted waves. One of the simple implementations of the technique is the usage of oblique background radiation. The results can be applied for the imaging of biological objects.

Recent years have seen a new wave of interest in layered media – namely, plasmonic multilayers – in several emerging applications ranging from transparent metals to hyperbolic metamaterials. In this paper, we review the optical properties of such subwavelength metal–dielectric multilayered metamaterials and describe their use for light manipulation at the nanoscale. While demonstrating the recently emphasized hallmark effect of hyperbolic dispersion, we put special emphasis to the comparison between multilayered hyperbolic metamaterials and more broadly defined plasmonic-multilayer metamaterials A number of fundamental electromagnetic effects unique to the latter are identified and demonstrated. Examples include the evolution of isofrequency contour shape from elliptical to hyperbolic, all-angle negative refraction, and nonlocality-induced optical birefringence. Analysis of the underlying physical causes, which are spatial dispersion and optical nonlocality, is also reviewed. These recent results are extremely promising for a number of applications ranging from nanolithography to optical cloaking.

In this review, we explore recent trends in optical micromanipulation by engineering light-matter interaction and controlling the mechanical effects of optical fields. One central theme is exploring the rich phenomena beyond the now established precision measurements based on trapping micro beads with tightly focused beams. Novel synthesized beams, exploiting the linear and angular momentum of light, open new possibilities in optical trapping and micromanipulation. Similarly, novel structures are promising to enable new optical micromanipulation modalities. Moreover, an overview of the amazing features of the optics of tractor beams and backward-directed energy fluxes will be presented. Recently the so-called effect of negative propagation of the beams (existence of the backward energy fluxes) has been confirmed for X-waves and Airy beams. In the review, we will also discuss the negative pulling force of structured beams and negative energy fluxes in the vicinity of fibers. The effect is achieved due to the interaction of multipoles or, in another interpretation, the momentum conservation. Both backward-directed Poynting vector and backward optical forces are counter-intuitive and give an insight into new physics and technologies. Exploiting the degrees of freedom in synthesizing novel beams and designed microstructures offer attractive prospects for emerging optical manipulation applications.

We theoretically study the characteristics of photoelectron emission in plasmonic nanoparticle arrays. Nanoparticles are partially embedded in a semiconductor, forming Schottky barriers at metal/semiconductor interfaces through which photoelectrons can tunnel from the nanoparticle into the semiconductor; photodetection in the infrared range, where photon energies are below the semiconductor band gap (insufficient for band-to-band absorption in semiconductor), is therefore possible. The nanoparticles are arranged in a sparse rectangular lattice so that the wavelength of the lattice-induced Rayleigh anomalies can overlap the wavelength of the localized surface plasmon resonance of the individual particles, bringing about collective effects from the nanoparticle array. Using full-wave numerical simulations, we analyze the effects of lattice constant, embedding depth, and refractive index step between the semiconductor layer and an adjacent transparent conductive oxide layer. We show that the presence of refractive index mismatch between media surrounding the nanoparticles disrupts the formation of a narrow absorption peak associated with the Rayleigh anomaly, so the role of collective lattice effects in the formation of plasmonic resonance is diminished. We also show that 5 to 20-times increase of photoemission can be achieved on embedding of nanoparticles without taking into account dynamics of ballistic electrons. The results obtained can be used to increase efficiency of plasmon-based photodetectors and photovoltaic devices. The results may provide clues to designing an experiment where the contributions of surface and volume photoelectric effects to the overall photocurrent would be defined., Comment: 9 pages, 7 figures

Optical properties of a one-dimensional photonic structure consisting of Kerr-type nonlinear and magnetic layers under the action of an external static magnetic field in the Faraday geometry are investigated. The structure is a periodic arrangement of alternating nonlinear and magnetic layers (a one-dimensional photonic crystal) with one of the layers doubled to create a defect where periodicity is violated. Strong enhancement of nonreciprocity is observed at the frequencies of the defect modes, where linearly polarized light incident from one side of the structure undergoes 90 deg polarization rotation upon reflection, while light reflected from the other side has its polarization unchanged. Using the nonlinear transfer matrix calculations in the frequency domain, it is demonstrated that defect resonances in the nonlinear reflection spectra undergo bending, resulting in polarization bistability of reflected light. This bistability is shown to result in abrupt switching between linear polarization of the output reflected light when the input intensity is varied. This switching is confirmed in finite-difference time-domain simulations, and its hysteresis character is established., Comment: 12 pages, 7 figures

We present a detailed theoretical description of the optical properties of planar metamaterials comprising a metal membrane patterned with openings (microslots) arranged in closely located couples (dimers). Using the covariant coupled-dipole approach, the effective material tensors of such a metamaterial are recovered, and contributions responsible for elliptical dichroism and optical activity are identified. Polarization conversion properties of II-shaped and V-shaped dimers are determined and explained in terms of elliptically polarized eigenmodes of the metamaterial. Good agreement with direct numerical simulations is demonstrated. The results obtained are promising for the design of thin-film frequency selective polarization shapers for terahertz waves.

We present a theoretical description of slab and ridge waveguides with multilayer claddings, such as Bragg reflection waveguides (BRWs), using analytical expressions based on Fresnel and Airy formulas. This approach simplifies the waveguide calculations in comparison with more traditional techniques such as the transfer matrix method or direct stitching of plane-wave solutions at layer interfaces. Approximate but simple and straightforward analytic relations describing the effective indices and group velocities of guided modes in arbitrary 1D BRWs are derived. The formalism is then extended to 2D ridge waveguides using the effective index method. The approach is employed to engineer BRWs where several types of phase matching are present simultaneously at the same wavelength, as well as BRWs where photons generated by spontaneous parametric downconversion have the maximal degree of polarization entanglement. These results promote the use of BRWs as on-chip entangled photon sources, and facilitate on-chip generation of multiple optical Bell states. The designs are based on the AlGaAs fabrication platform and are within reach of experimental realization.

A planar Babinet-inverted dimer metamaterial possessing strong optical activity is proposed and characterized. An original fabrication method to produce large area (up to several cm2) freely suspended flexible metallic membranes is implemented to fabricate the metamaterial. Its optical properties are characterized by terahertz time-domain spectroscopy, revealing anisotropic transmission with high optical activity. A simple coupled resonator model is applied to explain the principal optical features of the dimers, with predictive power of positions and number of resonances through a parametrical model. The model is validated for correct polarization-dependent quantitative results on the optical activity in transmission spectra. The fabrication method presented in this work as well as the slit dimer design has great potential for exploitation in terahertz optics.

The optical spectra of fractal multilayer dielectric structures have been shown to possess spectral scalability, which has been found to be directly related to the structure's spatial (geometrical) self-similarity. Phase and amplitude scaling relations, as well as effects of finite structure size, have been derived., 7 pages, 5 figures

Spontaneous emission enhancement is theoretically investigated in multiperiodic metal-dielectric multilayers (multiperiodic hyperboliclike metamaterials or photonic hypercrystals) where the unit cell consists of two layers of different dielectrics alternating with identical metallic layers. It is shown that the Purcell factor in such multiperiodic structures exceeds the Purcell factor in ordinary periodic hyperbolic or plasmonic metamaterials by a factor of 4, which in general makes it possible to maximize interaction between emitting centers and nearby plasmonic structures. This enhancement is numerically characterized and shown to be related to the interplay between surface and volume plasmonic excitations in the multilayer metamaterial. We separately identify the influence of proximity between the emitter and the closest metal-dielectric boundary (including the quenching effect and the enhanced coupling of the dipole radiation and surface plasmon polaritons) and the effects related to the structural composition of the hypercrystal. The Purcell-factor modification brought about by placing a cavity layer into a multiperiodic structure was also characterized.

The effect of external electric fields on the photoluminescence of quantum-sized nanocrystals of cadmium selenide excited by photons of various energies is studied. Photoluminescence quenching by external electric fields is found to be different for nanoparticles with different shapes (quantum dots and nanorods) and does not depend on the exciting photon energy. The relationship between the strength of the external electric field and the degree of quenching is determined empirically for both types of nanoparticles. A possible mechanism for the effect of an external electric field on the excitation and quenching of photoluminescence in quantumsized nanoparticles is discussed.

An alternative, fleld-based formulation of transformation optics is proposed. Field transformations are expressed in the language of boundary conditions for the electromagnetic flelds facilitated through the introduction of generalized potential functions. It is shown that the fleld-based approach is equivalent to the conventional coordinate-transformation approach but is preferable when looking for speciflc fleld distribution. A set of example devices such as invisibility cloaks, concentrators, rotators, and transformation optics lenses capable of creating light beams with predetermined fleld distribution (e.g., Gaussian and sinusoidal) is studied to validate the efiectiveness of the fleld-based formulation. As for the boundary conditions for the cloaked region the absence of the normal component of the Poynting vector is justifled. In the frames of the fleld- based approach the physical reasons behind inflnite components (singularities) of the material parameters of transformation optics devices are straightforwardly revealed.

Numerous nanophotonics applications involve the spatial confinement of the electromagnetic field to a length scale comparable to the optical wavelength, such as in photonic crystal (PhC) cavities or defects or in microlasers. First, we review a recently proposed, novel optimization scheme for the efficient construction of maximally localized photonic Wannier functions to be used as a set of basis functions for the description of localized modes in PhCs. We then analyze bistable lasing and the mode switching dynamics in multimode PhC microlasers and describe a recently developed theory for the confined, spatial intensity correlations (second-order coherence) in homogeneously disordered random lasers. Finally, a systematic diagrammatic expansion for the eigenmode renormalization of microlaser cavities due to the laser nonlinearity is described.

We review the basic physics behind light interaction with plasmonic nanoparticles. The theoretical foundations of light scattering on one metallic particle (a plasmonic monomer) and two interacting particles (a plasmonic dimer) are systematically investigated. Expressions for effective particle susceptibility (polarizability) are derived, and applications of these results to plasmonic nanoantennas are outlined. In the long-wavelength limit, the effective macroscopic parameters of an array of plasmonic dimers are calculated. These parameters are attributable to an effective medium corresponding to a dilute arrangement of nanoparticles, i.e., a metamaterial where plasmonic monomers or dimers have the function of "meta-atoms". It is shown that planar dimers consisting of rod-like particles generally possess elliptical dichroism and function as atoms for planar chiral metamaterials. The fabricational simplicity of the proposed rod-dimer geometry can be used in the design of more cost-effective chiral metamaterials in the optical domain., submitted to Appl. Phys. B

By now superresolution imaging using hyperbolic metamaterial (HMM) structures – hyperlenses – has been demonstrated both theoretically and experimentally. The hyperlens operation relies on the fact that HMM allows propagation of waves with very large transverse wavevectors, which would be evanescent in common isotropic media (thus giving rise to the diffraction limit). However, nearly all hyperlenses proposed so far have been suitable only for very strong scatterers – such as holes in a metal film. When weaker scatterers, dielectric objects for example, are imaged then incident light forms a very strong background, and weak scatterers are not visible due to a poor contrast. We propose a so-called dark-field hyperlens, which would be suitable for imaging of weakly scattering objects. By designing parameters of the HMM, we managed to obtain its response in such way that the hyperlens structure exhibits a cut-off for waves with small transverse wavevectors (low-k waves). This allows the structure to filter out the background illumination, which is contained in low-k waves. We numerically demonstrate that our device achieves superresolution imaging while providing the strong contrast for weak dielectric scatterers. These findings hold a great promise for dark-field superresolution, which could be important in real-time dynamic nanoscopy of label-free biological objects for example. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

We report on theoretical analysis and experimental validation of the applicability of the effective medium approximation to deeply subwavelength (period ⩽λ/30) all-dielectric multilayer structures. Following the theoretical prediction of the anomalous breakdown of the effective medium approximation [H. H. Sheinfux et al., Phys. Rev. Lett. 113, 243901 (2014)] we thoroughly elaborate on regimes, when an actual multilayer stack exhibits significantly different properties compared to its homogenized model. Our findings are fully confirmed in the first direct experimental demonstration of the breakdown effect. Multilayer stacks are composed of alternating alumina and titania layers fabricated using atomic layer deposition. For light incident on such multilayers at angles near the total internal reflection, we observe pronounced differences in the reflectance spectra (up to 0.5) for structures with different layers ordering and different but still deeply subwavelength thicknesses. Such big reflectance difference values resulted from the special geometrical configuration with an additional resonator layer underneath the multilayers employed for the enhancement of the effect. Our results are important for the development of new homogenization approaches for metamaterials, high-precision multilayer ellipsometry methods and in a broad range of sensing applications.

Terahertz (THz) radiation is gaining momentum in biology, medicine, communication, security, chemistry, and spectroscopy applications. To expand the usability of terahertz radiation the man-made metal-dielectric composite metamaterials are typically considered owing to their ability to effectively manipulate electromagnetic waves. The possibilities of light manipulation can be extended even more by involving new active materials as a structural component – such as, for example, graphene. Its prominent conductivity tunability through the electrochemical potential change allows converting a multilayer graphene/dielectric structure into an artificial medium with widely varying properties – transparent or opaque, plasmonic, low-index or high-index dielectric – in a certain THz or infra-red frequency range. This chapter presents several examples of effective THz components like absorbers, modulators, and filters based on graphene-dielectric multilayers.

Two methods suitable for numerical modelling of microlasers (including photonic crystal, microcavity, and random lasers) are presented. Finite-difference time-domain (FDTD) method and a generalized coupled mode theory are discussed in the context of microstructured resonators. The cases of one mode and two modes with near-identical properties but different frequencies are investigated in detail. The predictions of the coupled mode model are compared to FDTD simulations of a microcavity laser based on a single defect and twin coupled defects in a photonic crystal lattice. Different regimes of the mode competition (simultaneous and bistable lasing) are analyzed.

We reveal an outstanding potential of water as an inexpensive, abundant and bio-friendly high-refractive-index material for creating tunable all-dielectric photonic structures and metamaterials. Specifically, we demonstrate thermal, mechanical and gravitational tunability of magnetic and electric resonances in a metamaterial consisting of periodically positioned water-filled reservoirs. The proposed water-based metamaterials can find applications not only as cheap and ecological microwave devices, but also in optical and terahertz metamaterials prototyping and educational lab equipment.

We experimentally demonstrate the effect of anomalous breakdown of the effective medium approximation in all-dielectric deeply subwavelength thickness ($d \sim\lambda/160-\lambda/30$) multilayers, as recently predicted theoretically [H.H. Sheinfux et al., Phys. Rev. Lett. 113, 243901 (2014)]. Multilayer stacks are composed of alternating alumina and titania layers fabricated using atomic layer deposition. For light incident on such multilayers at angles near the total internal reflection we observe pronounced differences in the reflectance spectra for structures with 10-nm versus 20-nm thick layers, as well as for structures with different layers ordering, contrary to the predictions of the effective medium approximation. The reflectance difference can reach values up to 0.5, owing to the chosen geometrical configuration with an additional resonator layer employed for the enhancement of the effect. Our results are important for the development of new high-precision multilayer ellipsometry methods and schemes, as well as in a broad range of sensing applications., Comment: 5 pages, 4 figures

We propose a nanophotonic waveguide modulator with bismuth ferrite as a tunable material. Due to near-zero losses in bismuth ferrite, modulation with up to 20 dB/μm extinction ratio and 12 μm propagation length is achieved.

We propose to consider multilayer spatial structures as numbers. An arbitrary finite sequence of layers with N values of a material parameter which determines the speed of wave propagation is considered as a number written in the numeration system with base N. Within the framework of this approach propagation of classical waves and quantum particles can be treated as number recognition. A problem is formulated of identification of a type among spatial sequences featuring unique spectral portraits versus spatial structure. It is shown possible to perform certain arithmetic operations by means of sequential propagation of waves through several structures. Using fractal Cantor structures as a representative example, spectral properties of waves are shown to reproduce certain properties of the corresponding numbers. A possibility is outlined to use the above approach for data storage. If a set of numbers possessing unique spectral portraits forms a complete set, then compact coding of arbitrary numbers will become possible.

Transition absorption of electromagnetic field energy by an electron passing through a boundary between two media with different dielectric permittivities is considered both classically and quantum mechanically. It is shown that transition absorption can make a substantial contribution to the process of electron photoemission from metals due to the surface photoelectric effect., 4 pages, 3 figures

We theoretically investigate general existence conditions for broadband bulk large-wavevector (high-k) propagating waves (such as volume plasmon polaritons in hyperbolic metamaterials) in subwavelength periodic multilayer structures. Describing the elementary excitation in the unit cell of the structure by a generalized resonance pole of a reflection coefficient, and using Bloch's theorem, we derive analytical expressions for the band of large-wavevector propagating solutions. We apply our formalism to determine the high-k band existence in two important cases: the well-known metal-dielectric, and recently introduced graphene-dielectric stacks. We confirm that short-range surface plasmons in thin metal layers can give rise to hyperbolic metamaterial properties, and demonstrate that long-range surface plasmons cannot. We also show that graphene-dielectric multilayers tend to support high-k waves and explore the range of parameters for which this is possible, confirming the prospects of using graphene for materials with hyperbolic dispersion. The approach is applicable to a large variety of structures, such as continuous or structured microwave, terahertz (THz) and optical metamaterials., Comment: 9 pages, 5 figures

We discuss electromagnetic fields and optical forces acting on microspheres made of extremely anisotropic medium. We propose an energy-based criterion for choosing an appro- priate solution of Maxwell’s equations inside the sphere when two solutions are singular at the center. We investigate the material parameters of a lossy hyperbolic-metamaterial sphere that can be pulled by a nonparaxial, gradientless Bessel beam.

We analyze and compare surface- and volume-based internal photoelectric effects from spherical nanoparticles, obtaining analytical expressions for the photoemission rate in both cases. Similar to results for a flat metal surface, one can show that the surface mechanism prevails, since it is unaffected by detrimental hot electron collisions. Transient absorption results from dielectric permittivity discontinuity at the nanoparticle boundary and leads to a substantial (by ∼5 times) increase of the photoelectron emission rate.

We propose and investigate several layouts of metal-insulator-metal waveguide with active core which can be utilized for dynamic switching in photonic integrated circuits. The active material, bismuth ferrite (BiFeO 3 ), is sandwiched between metal plates and changes its refractive index through partial switching of ferroelectric domain orientation under applied voltage. Both phase and amplitude modulations are envisaged.

Optics of hyperbolic metamaterials is revisited in terms of large-wavevector waves, evanescent in isotropic media but propagating in presence of extreme anisotropy. Identifying the physical nature of these waves as Bloch volume plasmon polaritons, we derive their existence conditions and outline the strategy for tailoring their properties in multiscale metamaterials.

We introduce multi-periodicity in plasmonic multilayers and develop a general theory for the description of their eigenwaves. We define the order of multi-periodicity as the number of different kinds of plasmonic interfaces present in the multilayer, and investigate the optical effects that arise as this order increases from one (simple periodic multilayers) to two (bi-periodic multilayers) and beyond. For example, we show the formation of additional photonic bands, multi-refringence of p-polarized light, Dirac and mixed states.

Photoconductive and photovoltaic properties of metamaterials comprising plasmonic nanocone arrays embedded in a semiconductor matrix are studied. Under uniform plane-wave illumination, directed photocurrent and electromotive force arise near asymmetrically shaped nanocones. The resulting giant photogalvanic effect is a plasmonic analogue of the bulk photovoltaic effect in ferroelectrics.

We show how to correctly extract the effective permittivity and permeability of plasmonic multilayers in the optical domain. For material parameters retrieval the classical Nicolson-Ross-Weir method is commonly used. However, its direct application leads to spurious zero-permittivity points and false permeability resonances in the case of total reflection from the slab. We offer a way to overcome this issue and retrieve correct constitutive parameters of plasmonic multilayers.

We introduce multiperiodicity in periodic metal-dielectric multilayers by stacking more than two types of metal and/or dielectric layers into the unit cell. A simple way to characterize arbitrary multiperiodic multilayers using permutation vectors is suggested and employed. Effects of multiperiodicity up to its fourth order are investigated. We demonstrate that various topologies of multiple-sheet isofrequency and dispersion surfaces exist for such plasmonic multilayers, including a photonic realization of nontrivial isolated Dirac cones.

We theoretically study the propagation of large-wavevector waves (volume plasmon polaritons) in multilayer hyperbolic metamaterials with two levels of structuring. We show that when the parameters of a subwavelength metal-dielectric multilayer ("substructure") are modulated ("superstructured") on a larger, wavelength scale, the propagation of volume plasmon polaritons in the resulting multiscale hyperbolic metamaterials is subject to photonic band gap phenomena. A great degree of control over such plasmons can be exerted by varying the superstructure geometry. When this geometry is periodic, stop bands due to Bragg reflection form within the volume plasmonic band. When a cavity layer is introduced in an otherwise periodic superstructure, resonance peaks of the Fabry-Perot nature are present within the stop bands. More complicated superstructure geometries are also considered. For example, fractal Cantor-like multiscale metamaterials are found to exhibit characteristic self-similar spectral signatures in the volume plasmonic band. Multiscale hyperbolic metamaterials are shown to be a promising platform for large-wavevector bulk plasmonic waves, whether they are considered for use as a new kind of information carrier or for far-field subwavelength imaging., 12 pages, 10 figures, now includes Appendix A

We theoretically investigate general existence conditions for broadband bulk large-wavevector (high- k ) propagating waves (such as volume plasmon polaritons in hyperbolic metamaterials) in arbitrary subwavelength periodic multilayers structures. Treating the elementary excitation in the unit cell of the structure as a generalized resonance pole of reflection coefficient and using Bloch’s theorem, we derive analytical expressions for the band of large-wavevector propagating solutions. We apply our formalism to determine the high- k band existence in two important cases: the well-known metaldielectric and recently introduced graphene-dielectric stacks. We confirm that short-range surface plasmons in thin metal layers can give rise to hyperbolic metamaterial properties and demonstrate that long-range surface plasmons cannot. We also show that graphene-dielectricmultilayers tend to support high- k waves and explore the range of parameters, where this is possible, confirming the prospects of using graphene for materials with hyperbolic dispersion. The suggested formalism is applicable to a large variety of structures, such as continuous or structured microwave, terahertz (THz) and optical metamaterials, optical waveguide arrays, 2D plasmonic and acoustic metamaterials.

Photoelectric properties of metamaterials comprising asymmetrically shaped, similarly oriented metallic nanoparticles embedded in a homogeneous semiconductor matrix are theoretically and numerically studied. The asymmetric shape of the nanoparticles is found to result in the existence of a preferred direction where “hot” photoelectrons are emitted from the nanoparticle surface under the action of the localized plasmonic resonance excited in the nanoparticles. The resulting directional photocurrent flow occurring when nanoparticles are uniformly illuminated by a homogeneous plane wave is the direct analogy of the photogalvanic effect known to exist in naturally occurring non-centrosymmetric media. This plasmonic bulk photovoltaic effect is intermediate between the inner photoelectric effect in bulk media and the outer photoelectric effect at macroscopic interfaces. The results obtained are valuable for characterizing photoemission and photoconductive properties of plasmonic nanostructures. They can find many uses for photodetection-related and photovoltaic applications.

In this work, we show theoretically and confirm experimentally that thin metal membranes patterned with an array of slot dimers (or their Babinet analogue with metal rods) can function as a versatile spectral and polarization filter. We present a detailed covariant multipole theory for the electromagnetic response of an arbitrary dimer based on the Green functions approach. The theory confirms that a great variety of polarization properties, such as birefringence, chirality and elliptical dichroism, can be achieved in a metal layer with such slot-dimer patterning (i.e. in a metasurface). Optical properties of the metasurface can be extensively tuned by varying the geometry (shape and dimensions) of the dimer, for example, by adjusting the sizes and mutual placement of the slots (e.g. inter-slot distance and alignment angle). Three basic shapes of dimers are analyzed: II-shaped (parallel slots), V-shaped, and T-shaped. These particular shapes of dimers are found to be sensitive to variations of the slots lengths and orientation of elements. Theoretical results are well supported by full-wave three-dimensional simulations. Our findings were verified experimentally on the metal membranes fabricated using UV lithography with subsequent Ni growth. Such metasurfaces were characterized using time-domain THz spectroscopy. The samples exhibit pronounced optical activity (500 degrees per wavelength) and high transmission: even though the slots cover only 4.3 % of the total membrane area the amplitude transmission reaches 0.67 at the resonance frequency 0.56 THz.

We theoretically demonstrate superior degree of control over volume plasmon polariton propagation and the Purcell effect in multi-period (4-layer unit cell) plasmonic multilayers, which can be viewed as multiscale hyperbolic metamaterials or multi-periodic photonic hyper-crystals.

We demonstrate that an integrated photonic Bragg Reflection waveguide (BRW) inherently produces polarization entangled photons.

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.

We theoretically compare surface- and volume-based photoelectron emission from spherical nanoparticles, obtaining analytical expressions for the emission rate in both mechanisms. We show that the surface mechanism prevails, being unaffected by detrimental hot electron collisions.

We propose and analyze the performance of a technique to generate mode and polarization hyperentangled photons in monolithic semiconductor waveguides using two concurrent type-II spontaneous parametric down-conversion (SPDC) processes. These two SPDC processes are achieved by waveguide engineering which allows for simultaneous modal phase matching with the pump beam in a higher-order mode. Paired photons generated in each process are cross polarized and guided by different guiding mechanisms, which produces entanglement in both polarization and spatial mode. Theoretical analysis shows that the output quantum state has a high quality of hyperentanglement by spectral filtering with a bandwidth of a few nanometers, while off-chip compensation is not needed. This technique offers a path to realize an electrically pumped hyperentangled photon source.

We study the emission of photoelectrons from plasmonic nanoparticles into a surrounding matrix. We consider two mechanisms of electron emission from the nanoparticles - surface and volume ones and use models for these two mechanisms which allow us to obtain analytical results for the photoelectron emission rate from a nanoparticle. Calculations have been carried out for a step potential at the surface of a spherical nanoparticle, and a simple model for the hot electron cooling has been used. We highlight the effect of the discontinuity of the dielectric permittivity at the nanoparticle boundary in the surface mechanism, which leads to a substantial (by similar to 5 times) increase of the internal photoelectron emission rate from a nanoparticle compared to the case when such a discontinuity is absent. For a plasmonic nanoparticle, a comparison of the two photoeffect mechanisms was undertaken for the first time which showed that the surface photoeffect can in the general case be larger than the volume one, which agrees with the results obtained for a flat metal surface first formulated by Tamm and Schubin in their pioneering development of a quantum-mechanical theory of photoeffect in 1931. In accordance with our calculations, this possible predominance of the surface effect is based on two factors: (i) effective cooling of hot carriers during their propagation from the volume of the nanoparticle to its surface in the scenario of the volume mechanism and (ii) strengthening of the surface mechanism through the effect of the discontinuity of the dielectric permittivity at the nanoparticle boundary. The latter is stronger at relatively lower photon energies and correspondingly is more substantial for internal photoemission than for an external one. We show that in the general case, it is essential to take both mechanisms into account in the development of devices based on the photoelectric effect and when considering hot electron emission from a plasmonic nanoantenna.

We theoretically demonstrate that nanocomposites made of colloidal semiconductor quantum dot monolayers placed between metal nanoparticle monolayers can function as multilayer hyperbolic metamaterials. Depending on the thickness of the spacer between the quantum dot and nanoparticle layers, the effective permittivity tensor of the nanocomposite is shown to become indefinite, resulting in increased photonic density of states and strong enhancement of quantum dot luminescence. This explains the results of recent experiments [T. Ozel et al., ACS Nano 5, 1328 (2011)] and confirms that hyperbolic metamaterials are capable of increasing the radiative decay rate of emission centers inside them. The proposed theoretical framework can also be used to design quantum-dot/nanoplasmonic composites with optimized luminescence enhancement. (C) 2014 Optical Society of America

Creating miniature chip scale implementations of optical quantum information protocols is a dream for many in the quantum optics community. This is largely because of the promise of stability and scalability. Here we present a monolithically integratable chip architecture upon which is built a photonic device primitive called a Bragg reflection waveguide (BRW). Implemented in gallium arsenide, we show that, via the process of spontaneous parametric down conversion, the BRW is capable of directly producing polarization entangled photons without additional path difference compensation, spectral filtering or post-selection. After splitting the twin-photons immediately after they emerge from the chip, we perform a variety of correlation tests on the photon pairs and show non-classical behaviour in their polarization. Combined with the BRW's versatile architecture our results signify the BRW design as a serious contender on which to build large scale implementations of optical quantum processing devices.

We investigate electromagnetic wave propagation in multilayered metal-dielectric hyperbolic metamaterials (HMMs). We demonstrate that high-k propagating waves in HMMs are volume plasmon polaritons. The volume plasmon polariton band is formed by coupling of short-range surface plasmon polariton excitations in the individual metal layers.