This PDF file contains the front matter associated with SPIE Proceedings Volume 11769, including the Title Page, Copyright information, and Table of Contents.

Welcome and Introduction to SPIE Conference 11769

The angular distribution of far-field light intensity scattered by a two-dimensional array of nanoparticles depends on the optical properties of individual nanoparticles and their spatial distribution. The latter factor affects the scattered far-field in a two-fold manner. One such effect is the modification of the multipole moments of each individual scatter as a consequence of multiple scattering of light between the nanoparticles. The other one is the distribution of phase of multipolar fields that interfere to form the far-field pattern, which originates from the spatial distribution of the nanoparticles. In this work, we utilize an effective medium model developed within the T-matrix framework to calculate the angle-resolved scattered far-field intensity of disordered arrays composed of high-index nanoparticles. We show that our model may be used to predict the optical spectra including both radiative (far-field interference) effects as well as the multiple scattering effects making it a computationally efficient and accurate approach to model nanoparticle arrays with positional disorder. We utilize the presented model to study the capability to engineer the scattering-to-absorption ratio as well as the scattering directionality via tailoring the spatial distribution of nanoparticles. Control over those properties is sought after in nanoparticle applications such as photovoltaics and affects the efficiency of dielectric metasurfaces.

The two-dimensional designer metasurfaces have been established as a new class of versatile and powerful optical solution for controlling the classical light in various degrees of freedom such as phase, amplitudes, polarization and angular momentum. Expanding the control capability of metasurface from classical light to quantum state of single photons is an emerging direction that can lead to a new regime of light-matter interaction and applications for quantum technology. In this talk, we will present our proposal and experimental demonstration of manipulating photonic quantum states enabled by an unprecedented design of metasurface. We show the control over the quantum states and the effective quantum interaction between single photons, which is impossible by traditional optics. Our work greatly empowers the operations and functionalities of optical quantum technologies.

Nanoscale photothermal effects enable important applications in cancer therapy, imaging, and catalysis. They also induce substantial changes in the optical response experienced by probing light, thus suggesting their application in all-optical modulation. In this work, we take advantage of the strong temperature modulation of the graphene conductivity to propose an all-optical technique of excitation and manipulation of plasmons in graphene and thin metallic films. Through spatial patterning of the temperature of electrons in a graphene film (which can be achieved from an optical grating formed by interfering two pump beams), the graphene conductivity acquires a periodic profile, enabling plasmons to be excited directly by diffraction of a probe beam in the imprinted thermal grating. We show that, when graphene is placed in the vicinity of a thin metallic film, this technique can be used to excite and manipulate the plasmons supported in this hybrid structure. Additionally, we demonstrate the ability of graphene, thin metals films, and graphene-metal hybrid systems to undergo photothermal optical modulation with depth as large as > 70% over a wide spectral range extending from the visible to the terahertz spectral domains. We envision the use of ultrafast pump laser pulses to raise the electron temperature of graphene during a picosecond timescale in which its mid-infrared plasmon resonances undergo dramatic shifts and broadenings, while visible and near-infrared plasmons in neighbouring metal films are severely attenuated by the presence of hot graphene electrons.

Dielectric metasurfaces have recently attracted much attention due to their ability to efficiently control light propagation, that is, its amplitude, phase and polarization, on micro- and macro- levels. Such metasurfaces also naturally allow for integration in compact optical setups due to their small sizes. An important issue of energy losses is also addressed by employing all-dielectric platform. Advancements in nanofabrication have enabled realization of metasurface-based high-resolution wavefront engineering devices, which have been employed in different imaging applications, for example, as metalenses, polarization filters, metaholograms, etc. Quantitative phase imaging is a powerful tool for the optical inspection of transparent samples in connection with biological and technical applications. By measuring thickness and/or refractive index profiles, phase imaging facilitates, for example, the observation of dynamic events in unstained cells. As such, it has become indispensable in biological imaging, wavefront correction and metrology. However, conventional cameras and photodetectors are inherently not sensitive to the phase of an incident lightwave. As a consequence, direct phase detection is challenging. Only by multiple intensity measurements or application of specialized interferometric schemes, the phase profile of an object can be in principle reconstructed. In this paper, we report on the ability of metasurfaces to contribute to quantitative phase imaging by independent control of the phase profiles in two orthogonal polarization states of an incident beam.

High index dielectric (HID) metasurfaces are gaining interest in nanophotonics due to their highly tunable optical response which stems from supporting both magnetic and electric resonances, and typically low material losses. These characteristics make them viable candidates for a variety of applications, which if based of silicon, could be in principle compatible with CMOS technology. Being geometrical in nature, the sensitivity of resonances of an isolated dielectric nanoresonator to the refractive index of a homogeneous environment is low. Hence, effort is needed to utilize them as sensors of their surrounding. Herein we discuss various physical aspects that govern the spectral response and sensitivity of HID particles and their metasurfaces to changes in their environment. The specific effects under study are the aspect ratio of a single HID antenna, interaction with a substrate, and the effect of interparticle coupling in amorphous metasurfaces. To provide optimal solutions for HID sensors, it is crucial to understand the interplay of the above effects and strive to attain a regime in which they work in tandem to maximize the sensitivity. We utilize the T-matrix method to carry out calculations with explicit HID nanoantennas as well as describe a computationally efficient and accurate T-matrix-based effective model of amorphous metasurfaces to describe their optical response, accounting for multiple scattering effects and the presence of the substrate. Using this approach, we elucidate how the investigated effects shape the sensitivity of a HID sensor and how to combine the various geometrical aspects to design a sensitive device.

In recent years, light with orbital angular momentum, or the so-called vortex beams, has been the subject of intense research, due to its applications in microscopy, telecommunications, and investigating the selection rules. Many efforts have been devoted to generate vortex beams using metasurfaces and metamaterials. However, most of them lack key properties in controlling the polarization, directionality and intensity of the light which is generated and directed from a localized radiation sources such as electron-beam induced emission. Recently, a photon-sieve structure has been designed, developed and characterized as an electron-driven photon source, which is formed by specific ordering of nanoholes in different sizes and lattices forming a helical arm in a thin layer of gold. Electron beams in a scanning electron microscope interacts with the surface of a photon-sieve structure acting as a broadband source of optical excitation. Both Chain plasmons and chiral surface plasmons are excited in this structure resulting in vortex beams propagating in vacuum. Here, we design a photon sieve structure that can generate vortex pairs, i.e., optical beams with entangled phase singularities of opposite signs associated with the topological charges. This phenomenon is experimentally studied utilizing a cathodoluminescence detector facilitated with angle-resolved mapping, polarimetry, and spectroscopy methods. Data obtained from the polarimeter suggests that the rotating behaviour of the vortices are caused by their orbital angular momentum rather than the polarization. Experimental data are further confirmed by numerical simulations suggesting that the interference between the propagating polaritons and reflection from the void ring is the main reason for observing counter propagating plasmons with opposite chirality in experimental images. We anticipate that this work presents a systematic method towards designing new generation of metasurfaces with the possibility to control directivity, angular momentum, and energy of the light beams.

The advent of ultrathin, dynamically tunable materials has sparked unprecedented interest in the possibility of extending the metamaterial concept to the temporal domain. In electromagnetics, near-zero-index materials offer giant nonlinearities in the near-visible, whereas at mid-IR and below layered materials such as graphene enable efficient modulation of their carrier density. Fuelled by the interest in applications such as nonreciprocity, as well as new amplification and harmonic generation schemes, the concept of time-varying media promises to open new territories across all wave realms. In this contribution, we present a range of avenues opened by temporal inhomogeneities for the trapping, dragging and boosting of electromagnetic waves. We first present a new strategy for coupling free-space radiation to surface waves. The evanescent character of surface waves implies that their excitation from free space demands the breaking of momentum conservation, and hence the engineering of spatial surface-inhomogeneities. We propose a completely new pathway towards efficient excitation of surface waves, based on the breaking of temporal symmetry. By proposing and modelling a realistic graphene experiment, we demonstrate that surface waves can be excited without the need for any surface inhomogeneities, by modulating in time the carrier density of a material. We then demonstrate how the conventional concept of motion may be extended by considering spatiotemporal modulation of electromagnetic parameters. We first show how a generalised form of optical drag can be achieved by engineering a travelling-wave modulation of both dielectric and magnetic response parameters. Remarkably, this novel optical drag is not subject to the conventional limitations imposed by special relativity on moving media, as the modulation can be induced by an external pump to sweep the material at superluminal velocities. When the phase velocity of this travelling-wave modulation approaches the speed of the waves in the pristine medium, light undergoes a localisation transition: waves are trapped within each period of this synthetically moving grating. We conclude by introducing a comprehensive theory describing how how such “luminal media” can grab electromagnetic field lines and compress them, while simultaneously amplifying them, and discuss potential surface-wave implementations.

Wealth of fascinating phenomena provided by artificial photonic structures sparks extensive research efforts in the studies of metamaterials, a special and perspective class of them being the hyperbolic metamaterials (HMMs). Strong HMMs optical anisotropy attained by the combination of metal and dielectric constituents underpins unusual hyperbolic dispersion of light in these artificial media, which marvels plethora of far-reaching applications in photonics. However the dynamics of ultrashort optical pulses in HMMs remains almost unexplored. In this work we experimentally investigate the interaction of femtosecond laser pulses with metal-nanorod based HMMs exhibiting the epsilon-near-zero (ENZ) spectral point, when extraordinary dielectric permittivity goes to zero yielding transition between topologically distinct elliptic and hyperbolic light HMM dispersion. We demonstrate a pronounced superluminal and slow propagation of laser pulses in the HMM, with the transition between these regimes and resonant character of these phenomena in the spectral vicinity of the ENZ point. We put forward a theoretical model of the superluminality and slow light, which leverages unusual case of laser pulse with spectral components in elliptic and hyperbolic dispersion at once. We believe our findings bring to life superior applications for future linear and nonlinear ultrafast photonics of HMMs harnessing of revealed exotic dynamics of optical field in these media.

In the framework of magneto-photonics, the optical properties of a material can controlled by an external magnetic field, providing active functionalities for applications, such as sensing and nonreciprocal optical isolation. For noble metals in particular, the inherently weak magnetooptical coupling of the bulk material can be greatly enhanced via excitation of localized surface plasmons (LSP) in nanostructured samples. Hyperbolic metamaterials therein provide the ideal platform to tune the plasmonic properties via careful design of the effective permittivity tensor. Here, we report on the magnetic circular dichroism of electric and magnetic dipole modes of a type II hyperbolic metasurface. Disk-shaped nanoparticles consist in stacks of alternating dielectric and metallic layers. Using an effective medium theory, we show that the optical properties of the system can be perfectly described by an anisotropic homogenized permittivity. Magnetic circular dichroism spectroscopy experiments are compared with plain gold disk samples and reveal a broadband magneto-optical response across the visible and near infrared spectral range. In particular, derivative-like spectral signatures at the resonances of the nanoparticles prove the induced dichroism for the two modes of the system. Results are interpreted in terms of magnetically induced spatial confinement/broadening of circular currents in the nanoparticles and are compared with a comprehensive numerical model based on the finite elements method using the real dimensions of the nanostructure. Spherical particles are employed as an analytical model system, allowing to generalize the contribution of electric and magnetic modes to the total magneto-optical response. More in detail, interaction cross sections are calculated as a weighted sum of the corresponding Mie coefficients. Utilizing a perturbative approach, we describe the magneto-optical effect in terms of linear changes in the cyclotron frequency of free charge carriers in the metal. By comparing our analytical model with full-wave numerical results, we can identify the contribution of electric and magnetic dipole modes to the spectrum and reproduce the spectral line shape we observe in the experiments for the hyperbolic nanoparticles.

Hereby, we present analysis of threshold generation in DFB laser based on isotropic medium with optical gain and hyperbolic metamaterial (HMM) forming together a periodic structure, namely photonic hypercrystal. We investigate possibility of controlling threshold modal spectrum enabled by exploiting dispersion of the HMM structure. For this purpose, we developed an original approach for threshold generation analysis based on modified transfer matrix method. We demonstrate that, changing the dispersion type of HMM medium, may lead to a number of interesting effects, such as generation of single-mode, controllable side-mode suppression or ultra-low generation threshold.

In this work, we further explore the possibility of inducing spatial dispersion in hyperbolic metamaterials to exploit new functionalities which cannot be predicted via local approximation. For this purpose, we employed a nonlocal effective medium approximation to investigate the alteration of the topology of an iso-frequency surface of 1D hyperbolic metastructures in the presence of spatial dispersion. Over the course of our analysis, we demonstrated that strong nonlocality, enabled by a proper design of the unit cell, can substantially influence electromagnetic response of an HMM structure. We believe that our analysis demonstrated that thoughtful consideration of nonlocality in HMM structures may lead to new interesting applications.

We employ the known in photonic crystals phenomenon of self-collimation (SC) for modifying the performance of invisibility cloaks composed of dielectric rod arrays. Incorporation in the cloak design two circular sections, supporting SC, allows for refusing from Transformation Optics (TO) based prescriptions for the cloak medium, which request too challenging material parameters. In addition to SC sections, unidirectional cloak contains two TO-based transition sections with easily realizable parameters of rod arrays. These sections control wave paths between cloak input and output and SC sections. At plane wave incidence, the designed cloak was found to provide as restoration of initial flat wavefront behind the hidden object, so significant reduction of wave scattering by the object.

In this study, we report Fano-like coupling of electromagnetic radiation to infinitely extended planar waveguiding modes of a spatially unbounded system, which specifically is a nanostructured thin film. Proposed design differs from conventional Fano-resonant systems, since conventional ones emerge from coupling to compact resonators with discrete spectrum. In this context, nanostructured thin films are explored by numerical simulations along with an analytical study, followed by the fabrication of the films by the ion beam sputtering method on nano-modulated substrates. Experimental results showed Fano-like resonances of high sensitivity to wavelength and incidence angle of the radiation. Hence, proposed design can be a potential candidate for frequency- and spatial filtering of light in transmission/reflection through/from such nanostructured thin films.

By exploiting the generalized form of Snell’s law, metasurfaces afford optical engineers a tremendous increase in degrees of design freedom compared to conventional optical components. These “meta-optics” can achieve unprecedented levels of performance through engineered wavelength-, angular-, and polarization-dependent responses which can be tailored by arranging subwavelength unit cells, or meta-atoms, in an intelligent way. Moreover, these metaatoms can be constructed from phase change materials which give the added flexibility of realizing reconfigurable metaoptics. Devices such as achromatic flat lenses and non-mechanical zoom lenses are becoming a reality through the advent of metasurface-augmented optical systems. However, achieving high-performance meta-optics relies heavily on proper meta-atom design. This challenge is best overcome through the use of advanced inverse-design tools and state-ofthe- art optimization algorithms. To this end, a number of successful meta-device inverse-design approaches have been demonstrated in the literature including those based on topology optimization, deep learning, and global optimization. While each has its pros and cons, multi-objective optimization strategies have proven quite successful do their ability to optimize problems with multiple competing objectives: a common occurrence in optical design. Moreover, multiobjective algorithms produce a Pareto Set of optimal solutions that designers can analyze in order to directly study the tradeoffs between the various design goals. In our presentation, we will introduce an efficient multi-objective optimization enabled design framework for the generation of broadband and multifunctional meta-atoms. Additionally, several meta-optic design examples will be presented, and future research directions discussed.

The new physics of open-dissipative, non-Hermitian systems have become a fruitful playground to uncover novel physical phenomena, even in exotic or counterintuitive ways, especially in optics and, more recently, also in acoustics. In this work, we propose a non-Hermitian metasystem in acoustics for the control of the sound field in two dimensions. The building blocks, or meta-atoms composing the arrangements, are pairs of identical Helmholtz resonators with different gain or loss functions. Such Helmholtz resonator dipoles may be designed to hold asymmetric scattering, as was theoretically analyzed and experimentally confirmed. Furthermore, aiming to create a complicated directivity, we explored different ensembles of Helmholtz resonator dipoles and numerically demonstrated a sound concentration with various configurations. The proposed non-Hermitian parity-time- symmetric dipoles made of a pair of Helmholtz resonators may be a potential artificial element for the creation of complex sound fields.

We investigate all-dielectric flattened ellipsoid particle on dielectric substrate for demonstration of hybrid anapole mode. We find that such particle could support first and second order electric and magnetic anapole modes that manifesting fully eliminated scattering of the structure. We demonstrate scattering properties of high index all-dielectric ellipsoid particle and provide multipole decomposition on the scattering minimum.

The laser technology has been developed for fabricating structures from composite layers based on biopolymers: albumin, collagen, and chitosan with single-walled carbon nanotubes (SWCNT). The structures are intended for cardiovascular devices and tissue-engineered implants. The composite layers were fabricated due to the phase transition of biopolymers and SWCNT aqueous dispersion under the influence of laser pulses with the developed laser setup. At the same time conductive networks of SWCNT were formed in the biopolymer matrix. The threshold energy fluence of laser pulses was determined (0.032-0.083 J/cm²) at which a bimodal distribution of pores was observed. Elecrtical conductivity of composite layers was obtained, conductivity values for layers fabricated by laser were higher (12.4 S/m) than those for layers by thermostat (4.7 S/m).

A platform where magnetism meets topology opens up wide possibilities for implementation of new ideas, such as the quantum anomalous Hall effect, the magnetoelectric effect, the axion insulator state. Among magnetic topological insulators, the MnBi2Te4/(Bi2Te3)n family has recently attracted a special interest. Here, the classic Bi2Te3 topological insulator is combined with a compatible magnetic MnBi2Te4. Interestingly, the MnBi2Te4/(Bi2Te3)n superlattices with different spacing (n) between the MnBi2Te4 septuplet layers self-organize both structurally and magnetically during standard (e.g. Bridgman) crystal growth. Mn in MnBi2Te4 is oriented planarly, forming a 2D ferromagnet with the out-of-plane easy axis. The interplay between magnetism of this highly-ordered layer and the topology of Bi2Te3 is manifested in the high-temperature quantum anomalous Hall effect (Nature Physics (2020), DOI: 10.1038/s41567-020-0998-2) due to breaking down the time-reversal symmetry. In this communication I will discuss the influence of the MnBi2Te4 septuplet layer on the electronic structure of topological surface states, which is very broad due to possible different surface terminations of MnBi2Te4/(Bi2Te3)n superlattice. This problem is currently controversial due to many, often contradictory literature reports, and the assignment of the bands is still under discussion. Next, I will present the complex magnetism of MnBi2Te4/(Bi2Te3)n, which consists of both intra-layer interactions between Mn spins in MnBi2Te4 and inter-layer interactions between individual septuplet layers. Understanding magnetism and its effect on surface states is critical to applying the material to new phenomena. We would like to acknowledge NCN (Poland) grant no 2016/21/B/ST3/02565.

In this work, mechanically, chemically, and thermally resistant broadband and broad-angle antireflection coatings were prepared on 10 cm diameter glass substrates combining sol−gel deposition with nanoimprint lithography. The coatings are composed of water-repellent methylated silica (Si₄O₇Me₂) and exhibit a transverse refractive index gradient created by tapered, nipple-dimple, subwavelength nanostructures, featuring a record vertical aspect ratio of ∼1.7. The structure is composed of hexagonal arrays of nanopillars (∼200 nm height, ∼120 nm width) and holes (∼50 nm depth, ∼100 nm width) with a 270 nm pitch. The corresponding effective refractive index is between 1.2 and 1.26, depending on the fabrication conditions. Total transmission for double-face nanoimprint wafers reaches 96−97% in the visible range; it is limited by specular reflection and mostly by the intrinsic diffusion of the glass substrate. The antireflective effect is effective up to an ∼60° incidence angle. We address the robustness of the inorganic-based coating in various realistic and extreme conditions, comparing them to the organic perfluoropolyether (PFPE) counterpart (master reference). The sol−gel system is extremely stable at high temperature (up to 600 °C, against 200 °C for the polymer reference). Both systems showed excellent chemical stability, except in strong alkaline conditions. The inorganic nanostructure showed an abrasion resistance of more than 2 orders of magnitude superior to the polymer one with less than 20% loss of antireflective performance after 2000 rubbing cycles under an ∼2 N cm⁻² pressure. This difference springs from the large elastic modulus of the sol−gel material combined with an excellent adhesion to the substrate and to the specific nipple-dimple conformation. The presence of holes allows maintaining a refractive index gradient profile even after tearing out part of the nanopillar population. Our results are relevant to applications where transparent windows with broadband and broad-angle transmission are needed, such as protective glasses on photovoltaic cells or C-MOS cameras.

The field of plasmonics has the potential to enable unique applications in the different wavelength ranges, from the ultraviolet to the visible and the infrared. The choice of plasmonic material and how this material is nanostructured have significant implications for the ultimate performance of any plasmonic device. Nanoporous metals (NPMs) (such as Au, Ag, Cu, Al, Mg, and Pt) have intriguing material properties that offer potential benefits for many applications due to their high specific surface area, high electrical conductivity, and reduced stiffness. The research on nanoporous metals has taken place on various fronts, including advanced microfabrication and characterization techniques to probe unusual nanoscale properties and applications spanning from fuel cells to electrochemical sensors. Here we report a short review of the available nanoporous materials, looking in particular at their properties as plasmonic materials.

The phenomena of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, like a nanoparticle or a nanohole, the coupling between a broadband effect, i.e. scattering, and a discrete one such as surface plasmon excitation, leads to Fano-like plasmonic resonance line-shapes. The necessary phase matching requirements can be used to engineer the light-plasmon coupling and to achieve a directional plasmonic excitation. Here we investigate this effect by using a chiral nanotip to excite surface plasmons with a strong spin-dependent azimuthal variation. This effect can be described by a Fano-like interference with a complex coupling factor that can be modified thanks to a symmetry breaking nanostructure.

Effective control of electromagnetic radiation in the optical range is one of the key challenges in modern photonics. Recently, there has been a lot of research in the field of metamaterials – artificial subwavelength structures with specific optical properties defined by their geometry. It has been shown that such structures offer wide opportunities to manipulate light at the nanoscale. However, the fabrication of such structures is a technically challenging task. On the other hand, their 2d analogous - metasurfaces - based mainly on dielectric and semiconductor materials, are of greater interest due to the CMOS-compatibility and lower energy losses compared to their plasmonic counterparts. Recent research has shown the ability of metasurfaces to control the phase and amplitude of light waves on-demand with high efficiency, which paves the way for the creation of ultrathin elements such as metalenses, holograms and beam-shapers. They also can be used for optical analogue computing and processing of optical signals in real-time (such as differentiation, integration or convolution). These numerical studies allowed to demonstrate the result of the convolution of two images and obtain bright correlation peaks in the regions where the reference image was located in the analyzed one. Based on the achieved numerical results the sample of the silicon metasurface on a glass substrate was made by electron beam lithography and reactive ion etching techniques. Using this sample, a set of experimental tests was carried out to validate our numerical model. Achieved results can pave the way for the realization of new devices for analogue optical image processing based on CMOS-compatible metasurfaces.

The numerical studies of laser radiation focusing by the complex subwavelength diffractive axicons with different relief heights and refractive indices of axicon rings in the near zone are carried out in this paper (3D propagation). The Super- Gauss and an optical vortex with circular polarization were considered as the input laser radiation. It should be noted that the change in the height and refractive index of the relief of the optical elements made it possible, in the general case, to obtain better focusing in comparison with a conventional diffractive axicon with the same numerical aperture. In particular, it turned out to reduce the focal spot size by 15 percent for the case of an optical vortex.

We report on ultrafast opto-acoustic modulation of light reflectance in artificial epsilon-near-zero metamaterials made of two layers of Ag separated by an Al₂O₃ layer. By means of non-degenerate two color pump-probe experiments we demonstrate an optically induced acoustic modulation of the reflectance up to 20% via generation of acoustic waves inside the cavity upon mechanical expansion of the metal due to hot electron-phonon coupling nonlinearity in the Ag layers. The presented architecture opens the pathway towards novel routes to exploit light-matter interactions for opto-acoustic modulation at GHz frequencies. Moreover, our system can be designed to work in transmission geometry and is very versatile in terms of shifting the presented properties along a broad range of wavelengths, from UV to mid-IR. Our approach, beyond light-driven information processing, might impact also opto-mechanics, light-driven phonon induced up conversion mechanisms, non-linear optical and acoustic properties of materials, energy harvesting, and heat-assisted ultrafast magneto-optical recording.

The localized surface plasmon resonance (LSPR) of metal nanoantenna is significantly influenced by the size, shape, and environment but also its substrate. Here, we have used the epsilon-near-zero (ENZ) feature of hyperbolic metamaterial (HMM) as a substrate to manipulate the resonance of plasmonic nanoantennas. We demonstrate that the vanishing index of the substrate slows down the resonance shift of the antenna, known as pinning effect. Moreover, we have controlled the pinning effect at different regions by tuning the ENZ wavelength of HMM. This can be used for better manipulation of plasmonic structures used in flat optics and biosensing applications.

We study the crystal structure-mismatched, quantum dot-like (QD) composite metamaterial based on rock-salt narrow gap PbTe and zinc-blende wide gap CdTe. In the case of PbTe/CdTe QDs the quantum effects are observed for dots with dimensions of the order of 100 nm even at room temperature making this material system a promising candidate for mid-infrared applications. Using molecular beam epitaxy technique and utilizing difference in crystal structure of both semiconductors a variety of samples containing PbTe nanostructures with complicated morphology embedded in CdTe were obtained. Investigated nanocomposite PbTe/CdTe samples exhibit unusually strong and surprisingly narrow (about 5 meV) mid-infrared photoluminescence emission (250 meV) in contrast to the spectrally wide luminescence of a typical ensemble of PbTe/CdTe quantum dots measured in similar temperature (about 100 K) and excitation power conditions (400 microW). For excitation power exceeding 500 microW additional emission in energy about 15 meV lower than previous one appears, which dominates PL spectrum for excitation higher than 800 microW. This line, not reported for such kind of QDs yet, exhibit non-linear dependence of amplitude on excitation power. We discuss the observed behavior of photoluminescence considering presence of two-dimensional electron gas with high electron mobility and carrier density up to 10^19 cm-3 spontaneously formed close to the polar CdTe/PbTe interfaces. As estimated plasmon energy in our samples (240 meV) matches well the energy of observed emission, non-resonant coupling of photons with interface plasmons mediated by LO phonon is most possible explanation of unusual enhancement of PL from studied PbTe/CdTe metamaterial.