Dyakonov surface waves in dielectric crystals with negative anisotropy.

Since the initial discovery of Dyakonov surface waves at a flat infinite interface of two dielectrics, at least one of which is , extensive research has been conducted towards their theoretical and experimental studies in materials with positive anisotropy. The potential applications of these waves were initially limited due to the stringent conditions for their existence and the requirement for position anisotropy. In our study, we present the theoretical prediction and experimental observation of a novel type of Dyakonov surface waves that propagate along the flat strip of the interface between two dielectrics with .

The symmetry in the model of two coupled Kerr oscillators leads to simultaneous multi-photon transitions.

We consider the model of two coupled oscillators with Kerr nonlinearities in the rotating-wave approximation. We demonstrate that for a certain set of parameters of the model, the multi-photon transitions occur between many pairs of the oscillator states simultaneously. Also, the position of the multi-photon resonances does not depend on the coupling strength between two oscillators.

Ultrasensitive Nanophotonic Random Spectrometer with Microfluidic Channels as a Sensor for Biological Applications.

Spectrometers are widely used tools in chemical and biological sensing, material analysis, and light source characterization. However, an important characteristic of traditional spectrometers for biomedical applications is stable operation. It can be achieved due to high fabrication control during the development and stabilization of temperature and polarization of optical radiation during measurements.

Hybrid nanophotonic-microfluidic sensor for highly sensitive liquid and gas analyses.

Today, a lab-on-a-chip is one of the most promising ways to create sensor devices for gas and liquid analysis for environmental monitoring, early diagnosis, and treatment effectiveness assessment. On the one hand, this requires a large number of measurements and, on the other hand, involves minimum consumption of the test analytes. Combination of highly sensitive photonic integrated circuits (PICs) with microfluidic channels (MFCs) is necessary to solve this problem.

Laser Ablated Nanocrystalline Diamond Membrane for Infrared Applications.

We are reporting on laser microstructuring of thin nanocrystalline diamond membranes, for the first time. To demonstrate the possibility of microstructuring, we fabricated a diamond membrane, of 9 μm thickness, with a two-dimensional periodic array of closely located chiral elements. We describe the fabrication technique and present the results of the measurements of the infrared transmission spectra of the fabricated membrane.

Exciton Binding Energy in CdSe Nanoplatelets Measured by One- and Two-Photon Absorption.

Colloidal semiconductor nanoplatelets exhibit strong quantum confinement for electrons and holes as well as excitons in one dimension, while their in-plane motion is free. Because of the large dielectric contrast between the semiconductor and its ligand environment, the Coulomb interaction between electrons and holes is strongly enhanced. By means of one- and two-photon photoluminescence excitation spectroscopy, we measure the energies of the 1S and 1P exciton states in CdSe nanoplatelets with thicknesses varied from 3 up to 7 monolayers.

Gold nanoparticle-carbon nanotube multilayers on silica microspheres: Optoacoustic-Raman enhancement and potential biomedical applications.

There has been growing interest in recent years in developing multifunctional materials for studying the structure interface in biological systems. In this regard, the multimodal systems, which possess activity in the near-infrared (NIR) region, become even more critical for the possibility of improving examined biotissue depth and, eventually, data analysis. Herein, we engineered bi-modal contrast agents by integrating carbon nanotubes (CNT) and gold nanoparticles (AuNP) around silica microspheres using the Layer-by-Layer self-assembly method.

Stimuli-Responsive Microarray Films for Real-Time Sensing of Surrounding Media, Temperature, and Solution Properties via Diffraction Patterns.

Stimuli-responsive polymers have attracted increasing attention over the years due to their ability to alter physiochemical properties upon external stimuli. However, many stimuli-responsive polymer-based sensors require specialized and expensive equipment, which limits their applications. Here an inexpensive and portable sensing platform of novel microarray films made of stimuli-responsive polymers is introduced for the real-time sensing of various environmental changes.

Addressing the exciton fine structure in colloidal nanocrystals: the case of CdSe nanoplatelets.

We study the band-edge exciton fine structure and in particular its bright-dark splitting in colloidal semiconductor nanocrystals by four different optical methods based on fluorescence line narrowing and time-resolved measurements at various temperatures down to 2 K. We demonstrate that all these methods provide consistent splitting values and discuss their advances and limitations. Colloidal CdSe nanoplatelets with thicknesses of 3, 4 and 5 monolayers are chosen for experimental demonstrations.

Polarization control of quantum dot emission by chiral photonic crystal slabs.

We investigate theoretically the polarization properties of the quantum dot's (QDs) optical emission from chiral photonic crystal structures made of achiral materials in the absence of external magnetic field at room temperature. The mirror symmetry of the local electromagnetic field is broken in this system due to the decreased symmetry of the chiral modulated layer. As a result, the radiation of randomly polarized QDs normal to the structure becomes partially circularly polarized.

Mode solver based on Gegenbauer polynomial expansion for cylindrical structures with arbitrary cross sections.

We present a modal method for the computation of eigenmodes of cylindrical structures with arbitrary cross sections. These modes are found as eigenvectors of a matrix eigenvalue equation that is obtained by introducing a new coordinate system that takes into account the profile of the cross section. We show that the use of Hertz potentials is suitable for the derivation of this eigenvalue equation and that the modal method based on Gegenbauer expansion (MMGE) is an efficient tool for the numerical solution of this equation.

Derivation of plasmonic resonances in the Fourier modal method with adaptive spatial resolution and matched coordinates.

A very stable approach for finding optical resonances is to solve an eigenvalue equation that evolves from the linearization of the inverse scattering matrix. In this paper, we show how to use this approach in the Fourier modal method so that advanced coordinate transformation methods such as adaptive spatial resolution and matched coordinates can be included. Furthermore, we present a way that accelerates the computation of the inverse scattering matrix tremendously and allows the derivation of the resonant field distribution inside the structure efficiently.

Resonant mode coupling of optical resonances in stacked nanostructures.

We propose a method to obtain the resonance frequencies of coupled optical modes for a stack of two periodically corrugated slabs. The method is based on the modes in each slab, which are derived by the Fourier modal method in combination with the optical scattering matrix theory. We then use the resonant mode approximation of the scattering matrices to develop a linear eigenvalue problem with dimensions equal to the number of resonant modes.

Transverse photovoltage induced by circularly polarized light.

We discovered that when circularly polarized light is obliquely incident on a two-dimensional metallic photonic crystal slab, electrical voltage is induced perpendicular to the incident plane. The sign of the signal is reversed by changing the sense of polarization or incident angle. The origin of this transverse photoinduced voltage is explained in terms of the force proportional to the light intensity induced by the asymmetry, which is brought about by the angular momentum of the incident light, along with the modification of local near-surface electromagnetic fields in the slab and field enhancement due to surface plasmon resonance.

Matched coordinates and adaptive spatial resolution in the Fourier modal method.

Several improvements have been introduced for the Fourier modal method in the last fifteen years. Among those, the formulation of the correct factorization rules and adaptive spatial resolution have been crucial steps towards a fast converging scheme, but an application to arbitrary two-dimensional shapes is quite complicated.We present a generalization of the scheme for non-trivial planar geometries using a covariant formulation of Maxwell's equations and a matched coordinate system aligned along the interfaces of the structure that can be easily combined with adaptive spatial resolution.