In heterostructures for nanophotovoltaic (NPV) devices, a number of layers are concatenated in a multilayer configuration. In the analysis of a multilayer configuration, it is commonly assumed that the intensity of the optical field has an exponential decrease along the direction of propagation inside the structure. Effects such as reflections and interference are neglected. These neglected effects become especially important ones once the layer dimension reaches several nanometers. At this width regimen, quantum effects are present since layers are thin compared with the penetration depth and the wavelength of the incident light. Quantum effects influence photon absorption and affect the optical field dissipation that controls electron-hole pairs generation. Hence, dissipation of the optical field inside an NPV device is an important aspect to consider in studying and determining performance properties. We employed the one-dimensional optical transfer matrix theory and the quantum well theory to analyze the optical field dissipation in the active layer of heterostructures for NPV devices. Illumination of 100  mW·cm⁻² air mass 1.5 global (AM 1.5G) standard was considered for the analysis. The study was extended to low-dimensional heterostructures of the binary compound CdS/CdSe/CdS, the ternary compound Ga_0.9Al_0.1As/GaAs/Ga_0.9Al_0.1As, and the quaternary compound In_0.85Ga_0.15As_0.30P_0.70/In_0.7Ga_0.3As_0.6P_0.4/In_0.85Ga_0.15As_0.30P_0.70.

The theory of electromagnetically induced transparency (EIT) in a nonlinear conductive medium, which utilizes the classical approach instead of the traditional quantum optics scheme, has been recently suggested. We present the results of the bichromatic parametric irradiation experiments which validate the EIT effect within the mid-infrared spectrum. The studied materials include a highly dispersive gold (Au) and a low dispersive semiconductor zinc telluride (ZnTe). When the irradiation parameters satisfy the requirements of the EIT theory, the effect was shown to be strongly pronounced in both Au and ZnTe despite the very different optical properties of these conductors. The predictions of the theory regarding the existence of the EIT effect are shown to be in agreement with the experiment.

This paper presents the results of a numerical study of the optical mode confinement in whispering gallery mode disk nanocavities with hyperbolic dispersion using nanolayered Al/SiO₂ hyperbolic metamaterial with different Al fill fractions. The fundamental properties of the optical modes and resonance frequencies for the disk nanocavities are studied using the numerical finite-element method. Numerical simulations show that light can be well confined in a disk nanocavity with a radius of up to an order of magnitude smaller than free-space resonant wavelength. This paper will also focus on how Purcell factor and quality factor of the disk nanocavities are affected by the fill fraction of the aluminum in the nanolayered metamaterial. Potential future applications for disk nanocavities with hyperbolic dispersion include silicon photonics optical communications networks, ultrafast LEDs, and biological nanoparticles sensing.

Magneto-optical activity is demonstrated in thiolate-protected Au nanoparticles with magnetic circular dichroism (MCD) spectroscopy. The samples examined are decanethiolate-protected Au nanoparticles with the mean diameters ranging from 2.0 to 4.7 nm. The nanoparticles larger than 2.4 nm in diameter exhibit a derivative-like MCD signal, indicating the presence of two circular modes of surface magnetoplasmon, but the spectral shape is so asymmetric that its identification is rather difficult. This is due to the contribution of interband transitions occurring at around the localized surface plasmon resonance (LSPR) frequency. We then develop an efficient method to phenomenologically separate the effects of magnetoplasmonic intraband (= Drude) and interband transitions in the measured MCD spectra using an approximation that the optical response of the Au nanoparticle with a critical size (∼2.0  nm) for the disappearance of LSPR, which is also experimentally obtainable, is substantially dominated by the interband transitions. The consistency of the method is ensured for tiopronin-protected Au nanoparticles, and a very small bisignate magnetoplasmonic response hidden in the total MCD spectrum can be extracted. The practical advantage of the proposed method is that we can intuitively and effectively evaluate the characteristic features of the surface magnetoplasmon of thiolate-protected Au nanoparticles without performing complicated Mie or quasielectrostatic calculations.

The Heisenberg uncertainty principle is one of the cornerstones of quantum mechanics. We show that the observable values of the electromagnetic field in the far- and near-field zones emitted by the quantum nanoantenna are coupled via uncertainty relations of the Heisenberg type. The similar uncertainty inequalities are obtained for the electric currents in the different branches of the quantum networks. Based on these, we predict the mechanism of high-level squeezing of light in the quantum antennas. We show that this mechanism is highly directive. The strong values of squeezing are reaching in the narrow directions of high emission (tops of the main lobes of the radiation pattern). We also discuss the quantum noise manifestation in nanoelectronics and nanophotonics from the point of the electromagnetic compatibility of nanoelectronic devices, densely placed in the limited areas of space.

An intermediate reflector layer (IRL) serves as a spectrally selective layer between the top amorphous cell and bottom nanocrystalline cell in a micromorph silicon thin-film solar cell. In this paper, an IRL periodic design is proposed to achieve better conversion efficiency using thin active layers. The optically simulated short circuit current reaches 13.62  mA/cm² and three-dimensional electrical analysis shows a promising result. The design methodology used in this paper can be easily applied to different types of IRL materials and extended to triple thin-films solar cells. Finally, the results are compared with state-of-the-art design and further enhancement factors are discussed.

Gold nanoparticles and cysteamine-coated gold nanoparticles are physically synthesized using the pulsed laser ablation in liquid technique, which is rapid, simple, and efficient one-step synthesis. UV-Vis analysis shows that the absorption band after cysteamine coating is shifted toward the lower wavelength range around ∼234  nm as compared to gold nanoparticles’ absorption band around ∼520  nm. Moreover, the change in the color of the solution is due to the aggregation of nanoparticles after cysteamine coating. From transmission electron microscopy, cysteamine coating of ∼1  nm thickness on gold nanoparticles is successfully carried out with narrow pore size distributions. Energy-dispersive x-ray spectroscopy analysis confirms the presence of cysteamine coating. Attenuated total reflectance Fourier transform infrared spectroscopy analysis also confirms the bond linkage between gold and cysteamine species.

Vertical cavity surface emitting laser (VCSEL) plays a vital role in optical network. The present investigation reports the performance comparison of the modeling of single-mode VCSELs at room temperature for continuous wave operation. VCSEL for the study consists of InGaAsP-based cavity or active region sandwiched between GaAs/AlGaAs top mirror and GaAs/AlAs bottom mirrors with the aim of increasing the power conversion efficiency (PCE), lasing power, and decreasing the threshold current. It is observed that VCSELs with lower diameter are most suitable to achieve energy-efficient operation. The PCE obtained is ∼50% for the proposed single-mode VCSELs. The proposed VCSELs are suitable for short-reach optical interconnects such as chip-to-chip and board-to-board communication in high-performance computers.

In a conventional slot waveguide structure, light is strongly confined in the slot region only either for the quasi-transverse electric (TE) (in a vertically oriented slot) or for the quasi-transverse magnetic (TM) (in a horizontally oriented slot) fundamental eigenmode, which enhances the optical forces, thus decreasing the optical power necessary to control the displacement of the device, but only for one eigenmode polarization at a time. In this work, we analyzed the optical forces in a cross-slot waveguide, which is formed by four suspended silicon waveguides separated by two orthogonal air slots. Cross-slot waveguides can strongly confine light in both quasi-TE and quasi-TM polarizations, thus enhancing the optical force and reducing the optical power for both. Our simulation results show that by adjusting the optical power and the light polarization, it is possible to control the displacement of the waveguides in the vertical or in the horizontal direction almost individually, or in both directions simultaneously. The proposed nano-optomechanical device has potential applications in active photonic devices and novel mechanisms for nanosensors and nanoactuators, such as optical nanogrippers and nanotweezers.

Increasing the emission cross section of rare earth (RE) ions-doped transparent oxide glasses is a challenging issue. The incorporation of the metal nanoparticles (NPs) has been proposed as a promising approach to improve the emission properties, though the mechanism behind such a phenomenon is a controversial topic. Tellurite glass doped with Nd³⁺ ions and silver NPs is prepared and the optical absorption and emission properties are studied. The surface plasmon band of the silver NPs is observed at around 522 nm. Absorption and excitation bands of the Nd³⁺ ions are detected in the visible spectral region and associated to the transitions from ground state to various excited states. Threefold enhancement in the 1.06  μm luminescence of Nd³⁺ ions is observed under 800-nm laser excitation by incorporation of AgNO₃ up to 1 mol. %. Probable energy transfer and local field enhancements are discussed to explain the possible interactions between metal and RE ions.

We theoretically demonstrate ultradirectional, azimuthally symmetric forward scattering by dielectric cylindrical nanoantennas for futuristic nanophotonic applications in visible and near-infrared regions. Electric and magnetic dipoles have been optically induced in the nanocylinders at the resonant wavelengths. The cylindrical dielectric nanoparticles exhibit complete suppression of backward scattering and improved forward scattering at first generalized Kerker’s condition. The influence of gap between nanocylinder elements on the scattering pattern of the homodimers has been demonstrated. Further, for highly directive applications, a linear chain of ultradirectional cylindrical nanoantenna array has been proposed.

This work involves the development of a finite-element method model to examine the optical properties of two-dimensional photonic crystals (PCs). The model is capable of studying the effect of a finite number of periods in a PC structure. The new design minimizes computational resources by modeling a PC with one infinite dimension with periodic boundary conditions while modeling the second with finite dimensions. This allows for calculation of transmission and reflection spectra across the PC structure. A finite difference frequency domain (FDFD) model has been created for calculation of the photonic band structure. This is compared with the reflection spectra obtained through the reflection model and is found to closely match. The reflection model capabilities are demonstrated by calculating the reflection spectrum for various parameters: period length, number of periods, incident light polarization, and material properties. Effects of varying these parameters are demonstrated. For example, the reflectivity of a GaAs/Air PC was found to reach greater than 95% when the PC has 10 periods; it exceeds 99% with 13 periods and reaches 99.9% at 15 periods.

Strong Shubnikov-de Haas (SdH) oscillations were observed in the derivative of microwave absorption (f=10  GHz) in InAs/GaSb/AlSb composite quantum wells (CQWs) using electron-paramagnetic resonance spectroscopy at low temperatures (2.7 to 20 K) and in the magnetic field up to 14 kOe. CQWs were grown on n-GaSb:Te(100) and n-InAs:Mn(100) substrates with various widths of QWs by MOVPE. A predominant contribution to the bulk n-GaSb substrate in SdH oscillations was manifested. Two frequencies of the SdH oscillations connected with warping of the Fermi surface of GaSb were found from Fourier analysis. An unusual angular indicatrix was observed in dependence on the orientation of the samples grown on n-GaSb in the magnetic field. The obtained results can be explained by bulk inversion asymmetry, which is a feature of substances with a lack of inversion centers. For CQWs grown on n-InAs:Mn substrate, only several SdH oscillations with higher period were observed. We succeeded in extracting a contribution of the two-dimensional carriers of InAs QW∼H⊥, where [b]H⊥=H·cos Θ, from bulk substrate oscillations using a special spline interpolation from the angular dependence of SdH oscillatory amplitudes in the angle range of 0 to 90 deg.

The modification of the radiative decay of a single emitter in close vicinity to a dielectric interface is investigated by studying the photoluminescence (PL) decay dynamics of colloidal semiconductor nanocrystals (NCs) deposited on semiconductor surfaces. The PL decay lifetimes of single CdSe/CdS NCs spin-coated on InP surfaces passivated with thin oxide layers are measured. Electrochemical passivation of the InP surfaces with oxide layers of different thicknesses enables to study the influence of the distance between the semiconductor surface and the NC on the lifetime. A shortening of the PL decay lifetimes of the NCs with respect to their lifetimes on glass strongly suggests the opening of recombination channels for the photogenerated exciton, which we attribute to energy transfer between the NC and the semiconductor. We also experimentally show the influence of the orientation of the NC with respect to the semiconductor surface on the coupling.

HNbMoO₆-based nanocomposite material T-HNbMoO₆ is assembled by titania species dispersed on HNbMoO₆nanosheets (N-HNbMoO₆), which is obtained through the mechanical exfoliation of layered HNbMoO₆ (L-HNbMoO₆). The microstructures, skeleton features, and spectral-response characteristics of the as-prepared materials were characterized by means of technologies, such as powder x-ray diffraction, field emission scanning electron microscope with energy dispersive spectroscopy mapping, high-resolution transmission electron microscopy with energy dispersive x-ray spectrometer, N₂ adsorption–desorption isotherms, laser Raman spectroscopy, x-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, Mott–Schottky curves, and H₂ temperature-programmed reduction analysis. The photocatalytic activity was evaluated by the degradation of methylene blue dye under the Xe lamp irradiation. The results showed that the titania species are dispersed on the surface of N-HNbMoO₆ resulting from the interaction between guest titania species and host N-HNbMoO₆. T-HNbMoO₆ owns the best photocatalytic performance, which may be attributed to the synergistic effect between N-HNbMoO₆ and titania species.

A design of a highly sensitive multichannel biosensor based on photonic crystal fiber is proposed and analyzed. The suggested design has a silver layer as a plasmonic material coated by a gold layer to protect silver oxidation. The reported sensor is based on detection using the quasi transverse electric (TE) and quasi transverse magnetic (TM) modes, which offers the possibility of multichannel/multianalyte sensing. The numerical results are obtained using a finite element method with perfect matched layer boundary conditions. The sensor geometrical parameters are optimized to achieve high sensitivity for the two polarized modes. High-refractive index sensitivity of about 4750  nm/RIU (refractive index unit) and 4300  nm/RIU with corresponding resolutions of 2.1×10⁻⁵  RIU, and 2.33×10⁻⁵  RIU can be obtained according to the quasi TM and quasi TE modes of the proposed sensor, respectively. Further, the reported design can be used as a self-calibration biosensor within an unknown analyte refractive index ranging from 1.33 to 1.35 with high linearity and high accuracy. Moreover, the suggested biosensor has advantages in terms of compactness and better integration of microfluidics setup, waveguide, and metallic layers into a single structure.

A theoretical model is proposed to analyze the fabrication of metal nanopartical resist by metal nanofilm annealing, which is used in the manufacture of the transmission-enhanced subwavelength structures at the interface of the optical glass. Based on the conservation of volume of the metal before annealing and after heat treatment, the theoretical relationships of the structure parameters between the metal nanofilm and the metal nanoparticles are obtained. The experimental results coincide well with the theory model, which offers a theoretical guidance to fabricate subwavelength antireflected structures with the advantage of low cost achieved through metal nanofilm annealing. By this means, the average transmission of the quartz device intensifies to 97.9% for the structures fabricated on the both sides compared with the 93% for the unstructured one.

Enhancement of the performance of an InAs quantum dots (QDs) solar cell was investigated by using a nanostructured antireflection coating with hydrophobic properties. The surface modification was performed by growing ZnO nanoneedles on top of an InAs QDs solar cell’s surface, then the nanoneedles’ hydrophobicity treatment was achieved by using stearic acid. The QDs solar cell’s performance remarkably improved by 50% as noticed in the power conversion efficiency, external quantum efficiency, and spectral response after the surface modification. Additionally, the contact angle of the hydrophobic surface was found to be 153 deg.