This is a list of reviewers who served the Journal of Nanophotonics in 2019.

Light may carry both orbital angular momentum (AM) and spin AM. The former is a consequence of its helical wavefront, and the latter is a result of its rotating transverse electric field. Intriguingly, the light–matter interaction with such fields shows that the orbital AM of light causes a physical “twist” in a range of materials, including metal, silicon, azopolymer, and even liquid-phase resin. This process may be aided by the light’s spin AM, resulting in the formation of various helical structures. The exchange between the AM of light and matter offers not only unique helical structures at the nanoscale but also entirely novel fundamental phenomena with regard to the light–matter interaction. This will lead to the future development of advanced photonics devices, including metamaterials for highly sensitive detectors as well as reactions for chiral chemical composites. Here, we focus on interactions between the AM of light and azopolymers, which exhibit some of the most diverse structures and phenomena observed. These studies result in helical surface relief structures in azopolymers and will leverage next-generation applications with light fields carrying optical AM.

Within the formalism of the effective mass approximation, the Schrodinger equation is solved using a Hass variational method for a cubical GaAs/GaAlAs core/shell quantum dot. The impact actuated by the outside electric field, the hydrostatic pressure, the donor impurity off-center, and on-center effect, as well as the confinement geometric on the diamagnetic susceptibility, the polarizability, and the photoionization cross section (PCS), has been analyzed, taking into account the effect of the interaction electro–phonon (e–p). Our numerical results reveal that all of these principal parameters are very subject to the core and shell width. In addition, the impurity position and the electric field have a significant effect on the PCS without hydrostatic influence, especially when the impurity is situated at the center, and the situation becomes less significant in the boundaries of the system. On the other hand, it is found that the impact of both e–p interaction and hydrostatic influence causes a blueshift of the PCS. Interestingly, the polaronic effect is enhanced with the decreasing of the inner quantum dot width.

A new kind of super-high-intensity nano-emitting pixel, essentially adapted for augmented and virtual reality display applications, has been developed and simulated. In such a device, the pixels’ resolution is critical in order to offer a valuable use for military, professional, or consumer applications.

We propose, simulate, and achieve a method of realization of all-optical reversible logic gates based on nanoring dielectric-metal-dielectric plasmonic waveguides at 1550 nm and in the same structure. Finite-element method was used to study and simulate the proposed plasmonic reversible logic gates. These reversible logic gates are wire, NOT, swap, and Feynman. The working principle of the proposed reversible gates is based on the interferences (destructive or constructive) between the light that propagates in the input signal port(s) and control signal port(s). The threshold value of transmission between OFF and ON states is proposed as 0.4. Finally, the designed area of the proposed structure is very small (300  nm  ×  460  nm). These plasmonic reversible gates can contribute in construction of nanophotonic reversible logic circuits and all-optical quantum computing.

In the seed-mediated growth process of Au nanostructures, the uniformity and structures of the ultrafine seeds determine the purity and structures of the final Au products. Based on the highly shape-dependent surface plasmon resonance properties of Au nanostructures, we present the structures and structural transformation of Au seeds that have overgrown into Au nanostructures. The optical spectra and transmission electron microscopy images of the final product reflected that structures of the ultrafine seed are sensitive to the temperature and surfactants. It is found that the single-twinned Au seeds obtained at 30°C will transform into fivefold-twinned crystals at 90°C, which subsequently grow into Au nanobipyramids with a high surface plasmon resonance quality factor. The introduction of sodium citrate is beneficial for the formation of twinned crystal seeds. Hexadecyltrimethylammonium chloride can be used to keep the size of seeds small enough to allow Ostwald ripening at the initial heat treatment stage.

Controlling light with subwavelength-designed metasurfaces (MSs) has allowed for the arbitrary creation of structured light by precisely engineered matter. We report on the purity and conversion efficiency of hybrid orbital angular momentum (OAM)-generating MSs. We use a recently reported method to design and fabricate meta-surfaces that exploit generalized spin-orbit coupling to produce vector OAM states with asymmetric OAM superpositions, e.g., 1 and 5, coupled to linear and circular polarization states, fractional vector OAM states with OAM values of 3.5 and 6.5, and also the common conjugate spin and OAM of ±1 as reported in previous spin-orbit coupling devices. The OAM and radial modes in the resulting beams are quantitatively studied by implementing a modal decomposition approach, establishing both purity and conversion efficiency. We find conversion efficiencies exceeding 75% and purities in excess of 95%. A phase-flattening approach reveals that the OAM purity can be very low due to the presence of undesired radial components. We characterize the effect and illustrate how to suppress the undesired radial modes.

A rhombus-shaped holes-based photonic sensor is proposed and analyzed using the finite-difference time-domain method embedded in the commercial simulator RSoft. By changing the refractive indices in the biosensor under testing, the transmission properties of light are changed according to the changes in glucose concentrations. Various sensitivities are obtained and given as 604.5, 589.91, 537.86, and 520.5  nm  /  RIU, corresponding to both quality (Q) factors as high as 4.414  ×  10⁵, 2.1  ×  10⁵, 8.34  ×  10⁵, and 3.247  ×  10⁶ and a detection limit of 5.89  ×  10^−  7, 1.27  ×  10^−  6, 3.44  ×  10^−  7, and 8.99  ×  10^−  8, respectively. The obtained results were within the cavity region. Therefore, the Q factor and the sensitivity were significantly improved for the proposed structure, which makes this proposed design a potential and promising label-free biosensing device for the biomedical prognosis.

When metallic nanostructures are illuminated under resonance condition, part of the intercepted light is dissipated through nonradiative damping, resulting in a dramatic rise in temperature in the nanometer-scale vicinity of the particle surface. This nanoscale heat has been of great interest for applications in biomedicine and solar energy. We investigate the generation of heat in gold nanostructures at a constant metal volume and different morphologies under excited surface plasmonic resonance conditions using the finite-difference time-domain method and solving the thermal equation as well. Heat power as a measure of thermal efficiency has been obtained for different morphologies. Two kinds of structures including colloidal-like nanoparticles and lithographic planar nanostructures are discussed. It has been observed that as the surface-to-volume ratio in the structure increases, the heat power also increases along with a redshift, and the maximum increase is obtained for the porous structure. The amount of light transmission through porous nanostructure has also been investigated, compared with the nonporous structure, and it has been observed that they present better optical transmission. And therefore, they would have more desirable performance in multilayered structures. Moreover, the influence of surrounding medium on thermal and transmission characteristics of the nanostructures has been studied. Finally, the temperature distribution has been obtained for porous nanostructure for different absorbed powers by solving the heat transfer equation.

To obtain efficient and stable light trapping, angle rotation is introduced to form rotated square pillar array grating (SPAG) solar cells. Compared with the unpatterned stack slab and the optimized uniform SPAG cells, the maximum short-circuit current (J_sc) of the optimized rotated SPAG is increased by 78.54% and 3.21%, respectively. Moreover, besides the fact that the low-incidence angular sensitivity of J_sc could be maintained, J_sc of the optimized rotated SPAG will always be larger than that of the optimized uniform SPAG at any incident angle. Furthermore, when the structural parameters of the subsquare pillar slightly deviate from the optimum, the absorption only deceases slightly as well, which indicates both a high structural tolerance and a stable absorption performance. In addition, our results show not only that the proposed rotated SPAG is promising to make light trapping efficient and stable but also that introducing rotation disorders is promising for other high-absorption pseudounordered surface structures.

Stimulated emission depletion (STED), as one of the emerging super-resolution techniques, defines a state-of-the-art image resolution method. It has been developed into a universal fluorescent imaging tool over the past several years. The currently best available lateral resolution offered by STED is around 20 nm, but in real live cell imaging applications, the regular resolution offered through this mechanism is around 100 nm, limited by phototoxicity. Many critical biological structures are below this resolution level. Hence, it will be invaluable to improve the STED resolution through postprocessing techniques. We propose a deep adversarial network for improving the STED resolution significantly, which takes an STED image as an input, relies on physical modeling to obtain training data, and outputs a “self-refined” counterpart image at a higher resolution level. In other words, we use the prior knowledge on the STED point spread function and the structural information about the cells to generate simulated labeled data pairs for network training. Our results suggest that 30-nm resolution can be achieved from a 60-nm resolution STED image, and in our simulation and experiments, the structural similarity index values between the label and output result reached around 0.98, significantly higher than those obtained using the Lucy–Richardson deconvolution method and a state-of-the-art UNet-based super-resolution network.

We report on the observation of similar temperature dependences of PL intensities of AgInGaS nanoparticles and AgInGaS  /  GaS_x core–shell nanoparticles. The intensity of band-edge emission in AgInGaS  /  GaS_x increases with temperature up to 200 K, and the intensity at room temperature is on the order of that at 5 K. Using a model that includes effects of thermal activation of carriers from trap states, we propose that a shallow trap state exists in the AgInGaS core, and the higher PL intensity of the band-edge emission at 200 K is due to the radiative recombination of carriers that have been thermally activated from the shallow state. Time-resolved PL measurements are employed to support this interpretation.

A simple trilayer metamaterial absorber suitable for large area fabrication associated with a Fano-like resonance is numerically investigated and presented at infrared frequencies. The finite-element method-based COMSOL Multiphysics is used for numerical simulations and to understand the mechanism of absorption in the system. The absorber consists of photoresist disk arrays on a silicon substrate followed by a consecutive trilayer of gold, ZnS, and gold. The absorption is caused by the simultaneous excitation of the cavity and guided-mode resonances in the structures, whereas the Fano-like resonance arises due to the interference of these two modes. The coupled mode theory is used to describe the Fano-like resonance in the system. The design can easily be implemented for large area fabrications as it separates the structuring and deposition processes and makes them sequential, and avoids expensive and complex lift-off or etching processes. The spectral position of the resonance can be tuned by just controlling the thickness of the trilayer instead of the structural size and shape modification of the micro/nanostructures as is usually done in conventional metamaterial absorbers.

We report on the first demonstration of picosecond optical vortex-induced chiral surface relief in an azo-polymer film due to two-photon absorption isomerization. The chiral surface relief exhibits an extremely narrow defocusing tolerance without undesired outer rings due to the Airy pattern of highly focused light. Such chiral surface relief reflects a z-polarized electric field with an azimuthal helical phase caused by spin–orbital angular momentum coupling.

The binding energy, oscillator strengths, and absorption coefficients (ACs) for double ring-shaped quantum dots (DRSQDs) are theoretically investigated within the framework of effective mass approximation. The Schrödinger equation is solved by a variational method in order to compute the energy levels of a hydrogenic impurity in a gallium aresenide DRSQD. Obtained results have revealed the dependence of the binding energy on the dot radius and the potential parameters B and C. The energy values in the absence and presence of impurity are compared with the literature for spherical harmonic oscillator. The binding energy decreases as the quantum dot radius and the potential parameters increase. Also, it is found that the oscillator strengths and the linear and nonlinear optical ACs are quite sensitive to the potential parameters. The peaks of AC exhibit blueshift with B and C increasing.

All-dielectric metasurface (ADM) color filter arrays (CFA) are attractive for replacing conventional organic-dye color filters due to several advantages such as CMOS-compatibility, size scalability, and robustness to degradation. We propose metasurface designs with polygon-shaped unit cells for improving the performance of such filters. Our numerical results predict improvement in color purity for red, green, and blue primary color filters and significant reduction in insertion loss for blue filters as compared to the previously reported designs using simple circular shapes. The proposed differential evolution optimization methodology can be useful for improving the performance of other metasurface spectral filtering structures.

A single layer dual L-shaped graphene metasurface is presented to achieve a high operative and tunable polarization converter in the mid-infrared regime. The proposed device and numerical results indicate that linearly polarized wave can be converted to its cross-polarized wave. In addition, it can be used as a converter to a circularly polarized wave. This converter is insensitive to the angle of incident wave. Working frequencies can be easily and significantly tuned within a wide frequency range by regulating the chemical potential of the graphene. The physical procedure of the polarization conversion effect is explicated via coupling of the electric field components with various plasmon resonance modes of the metasurface. The suggested structure can pave a way to development of controllable plasmonic polarization converter systems for optical communication applications.

This erratum corrects an error in a sign in an equation.