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Due to their excellent optical properties, luminescent carbon dots can find application in various fields, including biomedicine, sensing, and optoelectronics, and in particular for the development of advanced white light- emitting diodes (LEDs). Herein, we developed a microwave-assisted colloidal synthesis of five types of carbon dots starting from o-phenylenediamine as a precursor. The emission of fabricated carbon dots can be tuned over a wide spectral range (430-590 nm) by using nitrogen-containing solvents or additional precursors of different nature, including organic acids and polymers. [ABSTRACT FROM AUTHOR]

In this work, we study optical properties of an array of dielectric periodic waveguides that possess two modes with identical frequencies and wavenumbers and characterized by the different symmetry with respect to the plane that contains the waveguide axis. Due to the presence of two modes, the field pattern of the wave excited in an individual waveguide can be highly asymmetric. We demonstrate that such a feature leads to the opening of the topological bandgap in the dispersion of the infinite array of equidistantly spaced identical two-mode waveguides. In agreement with the bulk-edge correspondence, the finite array of the waveguides supports two topological edge modes, regardless of the number of the waveguides in the array. [ABSTRACT FROM AUTHOR]

The chemical composition and optical properties of amorphous carbon films of various thicknesses in the range from 1 to 100 nm on a series of optical fibers were characterized by using far-and near-field Raman spectroscopy. For the first time the presence of a hysteresis of the resistance of a thin carbon film was observed in ambient environment. The Raman spectrum of carbon film in the region of 1000-2000 cm−1 was fitted and well reproduced using seven individual components that were assigned to the oxygen- and hydrogen-containing functional groups defect graphene. Besides that, the thermo-assisted Tip-Enhanced Raman Scattering (TERS) method provided the evidence of the formation of a water molecule in carbon coatings. We propose that during the heat treatment the fraction of functional groups on the initial film structures changes in comparison with room temperature. Such structural modifications of carbon film can lead to a violation of hydrophobic properties of carbon coatings due to temperature change. These findings may provide opportunities for technical design of carbon-based devices. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of plasmonic properties of electrically driven gold nanodisks employing scanning tunnel microscopy induced luminescence (STML). Gold disks were fabricated with the use of e-beam lithography. The size of the disks (diameter of 120-180 nm and height of 60 nm) was comparable with the wavelength emitted. To confirm that the observed emission of photons is associated with inelastic tunneling of electrons, but not with the collision of the probe with the nanodisk surface, the nanodisk was STML scanned at different angles of the probe motion (0, 90, 270 degrees). In all cases the obtained images were identical. It was shown that nanodisk provided nonuniform STML map, the edges of the nanodisk emitted light with higher intensity compared to the center. Also, current-voltage I(V) characteristics at different points of a nanodisk were obtained and analyzed, and the acquired features at I(V) curves were correlated to the STML results. The proposed approach based on I(V) curves analyzing is very promising for the indirect study of optical properties of the electrically driven nanoscale photon sources. [ABSTRACT FROM AUTHOR]

In recent years the attention of many researchers is riveted to the study the optical properties of two-dimensional semiconductors such as transition-metal dichalcogenide (TMD or TMDC) monolayers (MLs) which are looking highly promising both from the fundamental point of view and the practical application prospects. The complex band structure and reduced screening coulomb interaction formed there facilitate strong correlation phenomena. These correlation effects in terms of optical response reveal themselves through the specific optical resonances such as excitons, trions, etc., as well as strong optical nonlinearity. In this work we aim to demonstrate some initial steps of comprehensive computational machinery being developed to take into account many-particle effects which are widely observed in a huge number of experiments on TMD MLs conducted at present. As a starting point to describe the corresponding dynamics we address the Heisenberg equation of motion. Processing the quantity of interest we come to an infinite hierarchy of equations. In order to properly truncate this system we use the cluster expansion technique that allows together with several tricks to competently construct some kind of perturbative series for the analyzed equations. Subsequently, these expansions can be treated numerically. In particular, within the current letter we present lower two-particle corrections which contribute to interband polarization. [ABSTRACT FROM AUTHOR]

Plasmonic nanoparticles lattices in a dielectric environment demonstrate exceptional optical properties due to the combination of plasmonic structures' ability to confine light in deep subwavelength scale and dielectric ones to support high-quality optical modes. However, such structures, especially in the case of the small size of plasmonic particles, are hard for the calculation by the means of the Fourier modal method (FMM) specialized for periodic structures, since their local field is described by high-k|| harmonics. We propose not to account for a large number of harmonics, but to consider the lattice in discrete dipole approximation (DDA) to construct its scattering matrix. In this work, we apply this approach for lattices with several particles in a cell. The performance of the method is demonstrated on an example of the lattice on a waveguide that supports polarization controlled coupling of circularly polarized light to guided modes propagating in opposite directions. We show the high speed and precision of our approach, which allows us to use it both for the calculation of plasmonic lattices spectra and the design of nanophotonic devices based on such lattices. [ABSTRACT FROM AUTHOR]

To control light by magnetic field magneto-optical nanostructures can be used. Response of well-known periodical structures is narrowband and depending on light's incident angle. In present work we investigated magneto- optical properties of 2D periodic and quasicrystalline structures. These structures consist of gold grating-patterned layer on top of magnetic dielectric film. We showed that in 2D quasicrystalline structures magnetoplasmonic effects, such as the transverse magneto-optical Kerr effect (TMOKE) and Faraday effect, are broadband. Moreover, their independence of light's polarization and incident angle was demonstrated. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate the possibility of using local anodic oxidation (LAO) for fabricating optical devices based on thin transition metal dichalcogenides (TMDC) layers. By LAO we fabricated an optical cavity from 6-layered MoSe2 flake transferred on Si/Au substrate. Optical properties were investigated by measuring microphotoluminescence. The cavity exhibits three order of magnitude enhancement of the flake's photoluminescence, which is only one order of magnitude lower than the monolayer on a SiO2 substrate. Here we show that LAO is a high-precision lithography method suitable for fabricating optoelectronic devices made of thin TMDC layers. [ABSTRACT FROM AUTHOR]

Optical resonant properties of plasmonic helix arrays fabricated by focused ion beam induced deposition have been experimentally investigated in scattering. The resonances have been studied under different polarizations of the incident light, demonstrating a significant polarization dependent behaviour of these nanostructures in the visible spectral range. [ABSTRACT FROM AUTHOR]

In this work, we consider the optical properties of icosahedral quasicrystals. Quasicrystals were created by direct laser writing. This method of creation made it possible to create three-dimensional structures of high quality. Optical properties were investigated using optical diffraction. The diffraction patterns from such structures were experimentally recorded. [ABSTRACT FROM AUTHOR]

In this work, using the numerical simulation in the COMSOL Multiphysic package, we studied the optical properties of the hybrid anapole state in silicon nanocylinders and their metasurfaces. Our investigations show the possibility of creating invisible metasurfaces consisting of silicon cylinders based on the novel state. These results can be used in various fields of nanophotonics and may have important outcome in the development of various sensors and other photonic devices. [ABSTRACT FROM AUTHOR]

We demonstrate an optical induced switching of the optical properties of metal-organic frameworks soaked in advance in 1,4-dioxane, and dimetholeformamide. Near-infrared laser pulses stimulate reversible and fast blue shift of the absorption band of the framework. Such light-induced switching enables the remote modulation of optical properties of metal-organic frameworks and opens up the possibility of utilizing them for all-optical data processing. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate the fabrication of differently oriented laser-induced periodic surface structures (LIPSS) on hybrid metal-dielectric films. Dark-field and scanning electron microscopy images of obtained structures show a decrease in the size and period between them along the laser spot. The mapping of nonlinear optical properties of structures demonstrates two-order enhancement of SHG signal compared to the initial sample together with intense broadband photoluminescence signal. A comparison between maps and scanning electron microscopy images shows that the strongest nonlinear signal is detected in the region of the most densely located structures. We suppose that such type of structures can be used as a useful white light source for lab-on-chip devices. [ABSTRACT FROM AUTHOR]