Xiaodong Wang

In this paper, we propose a topological plasmonic 1D nanocavity, which comprises a dielectric nanoparticle chain placed on a metallic substrate. The structure is designed based on the topological characteristics of the plasmonic photonic crystals. A topological edge state exists at the interface between two distinct structures. In comparison to a non-topological defect mode, the topological edge mode exhibits better properties including good confinement and robustness against perturbations in scales and length–width ratio of the nanoparticles.

Quantum dot solar cells exhibit superior performance which can absorb low-energy photons and have less degradation in irradiation environments. In this paper, proton irradiated InAs/GaAs quantum dots and their solar cells are studied. The optical property shows that quantum dots exhibit higher radiation resistance compared to the wetting layer and GaAs bulk. Besides, the photoelectric character of solar cells further illustrates that the addition of quantum dots slows down the device’s performance degradation. Furthermore, results of external quantum efficiency reveal that the current generated by quantum dot layers hardly decreases after the irradiation. These findings show that the quantum dot solar cells have high radiation resistance and are promising to be used in a harsh environment.

Light trapping structures can enhance the absorption and reduce the thickness and costs of solar cells. Among light trapping structures, the metasurface structure utilizes Mie scattering to make light enter the solar active layer better, thus improving the photovoltaic conversion efficiency of solar cells. Herein, we simulated and optimized a metasurface light-trapping structure for solar cells and implemented this structure on solar cells. Simulation results of thin-film silicon-based solar cells show that the maximum short-circuit current can be increased to 24.46 mA/cm² using a metasurface light-trapping structure, which is an increase of 40.49% compared to the reference bare cell. In addition, when this metasurface structure is integrated into a crystalline silicon solar cell, we find that the maximum short-circuits current reaches 29.09 mA/cm², which is an even more significant improvement of 54.6% compared to the reference bare cell, and the power conversion efficiency increases by 7.14%. This study verifies the effect of a metasurface light-trapping structure on the light absorption of silicon-based solar cells.

Multifocal lenses are essential components for microscopy, spectroscopic detection, and optical trapping. Benefiting from the unprecedented capability of metasurfaces in light control, metalenses are able to provide multi-foci functionality with a more compact footprint, making them attractive alternatives to traditional bulky lenses. However, current manufacturing techniques encounter some challenges, including low throughput, high cost, and limited patterning areas. Here, we demonstrate the wafer-scale, low-cost, and high-throughput production of polarization-insensitive bifocal metalenses at a wavelength of 450 nm by combining nanoimprint lithography and atomic layer deposition. The nanoimprint process is simplified by using the imprinted resin itself as meta-atoms, which exhibit high aspect ratios (∼10:1) and small critical dimensions (∼90 nm). The effective refractive index of the meta-atoms is increased through atomic layer deposition of the high-index TiO2 film, providing 0–1.5π sufficient phase coverage. Metalenses with diameters of 480 μm are fabricated on the silica substrate, exhibiting two diffraction-limited focal spots along the optical axis. Moreover, the fabricated metalenses demonstrate the polarization-insensitive feature under various polarization states. The fabrication process presented in this Letter paves the way for large-scale and low-cost production of versatile metasurfaces operating in the visible or shorter spectrum.

In(Ga)As quantum dot (QD) with uniform size and controlled sites have great potential in optical communications and quantum computing. In this review, we focus on the site-controlled preparation of In(Ga)As quantum dot arrays based on patterned substrates, including the improvements made by the researchers to enhance the quantum dot site-control capability and optical quality. Based on the current research on site-controlled In(Ga)As QDs, it has been possible to grow uniformly ordered In(Ga)As QD arrays, in which the size, morphology, and nucleus location of each quantum dot can be precisely controlled. In addition, the study of deoxidation treatment of patterned substrates has led to the performance enhancement of the prepared QD arrays. Finally, we propose that the future development of site-controlled In(Ga)As QD arrays lies in improving the optical quality and tuning their emission wavelength to the telecommunication band.