Control of light absorbance using plasmonic grating based perfect absorber at visible and near-infrared wavelengths

1114Nsciescopu

Demonstration of nanoimprinted hyperlens array for high-throughput sub-diffraction imaging

11124Nsciescopu

Geometric metasurface enabling polarization independent beam splitting

A polarization independent holographic beam splitter that generates equal-intensity beams based on geometric metasurface is demonstrated. Although conventional geometric metasurfaces have the advantages of working over a broad frequency range and having intuitive design principles, geometric metasurfaces have the limitation that they only work for circular polarization. In this work, Fourier holography is used to overcome this limitation. A perfect overlap resulting from the origin-symmetry of the encoded image enables polarization independent operation of geometric metasurfaces. The designed metasurface beam splitter is experimentally demonstrated by using hydrogenated amorphous silicon, and the device performs consistent beam splitting regardless of incident polarizations as well as wavelengths. Our device can be applied to generate equal-intensity beams for entangled photon light sources in quantum optics, and the design approach provides a way to develop ultra-thin broadband polarization independent components for modern optics.113Nsciescopu

Metamaterial-Based Radiative Cooling: Towards Energy-Free All-Day Cooling

In the light of the ever increasing dangers of global warming, the efforts to reduce energy consumption by radiative cooling techniques have been designed, but are inefficient under strong sunlight during the daytime. With the advent of metamaterials and their selective control over optical properties, radiative cooling under direct sunlight is now possible. The key principles of metamaterial-based radiative cooling are: almost perfect reflection in the visible and near-infrared spectrum (0.3-3 mu m) and high thermal emission in the infrared atmospheric window region (8-13 mu m). Based on these two basic principles, studies have been conducted using various materials and structures to find the most efficient radiative cooling system. In this review, we analyze the materials and structures being used for radiative cooling, and suggest the future perspectives as a substitute in the current cooling industry.11Ysciescopu

KoMultiText: Large-Scale Korean Text Dataset for Classifying Biased Speech in Real-World Online Services

With the growth of online services, the need for advanced text classification algorithms, such as sentiment analysis and biased text detection, has become increasingly evident. The anonymous nature of online services often leads to the presence of biased and harmful language, posing challenges to maintaining the health of online communities. This phenomenon is especially relevant in South Korea, where large-scale hate speech detection algorithms have not yet been broadly explored. In this paper, we introduce "KoMultiText", a new comprehensive, large-scale dataset collected from a well-known South Korean SNS platform. Our proposed dataset provides annotations including (1) Preferences, (2) Profanities, and (3) Nine types of Bias for the text samples, enabling multi-task learning for simultaneous classification of user-generated texts. Leveraging state-of-the-art BERT-based language models, our approach surpasses human-level accuracy across diverse classification tasks, as measured by various metrics. Beyond academic contributions, our work can provide practical solutions for real-world hate speech and bias mitigation, contributing directly to the improvement of online community health. Our work provides a robust foundation for future research aiming to improve the quality of online discourse and foster societal well-being. All source codes and datasets are publicly accessible at https://github.com/Dasol-Choi/KoMultiText.Comment: Accepted to the NeurIPS 2023 Workshop on Socially Responsible Language Modelling Research (SoLaR

Corrigendum: Demonstration of nanoimprinted hyperlens array for high-throughput sub-diffraction imaging

11Ysciescopu

All-dielectric metasurface imaging platform applicable to laser scanning microscopy with enhanced axial resolution and wavelength selection

Metasurfaces composed of artificially fabricated nano-sized structures have shown extraordinary potential for the precise control of light. Here, we demonstrate for the first time, a metasurface application to reduce the axial size of the point spread function in laser scanning microscopy. The all-dielectric metasurface has wavelength selectivity over the whole visible range, and confinement of the excitation point spread function of the electromagnetic field. These two unique features allow the metasurface to be applied to laser scanning microscope systems. Numerical and experimental demonstrations of the proposed all-dielectric metasurface are reported, showing sharp implicit spectral filtering in the visible range and enhanced axial confinement by observing actin filaments in NIH3T3 cells. We believe that our approach can provide a useful insight on the practicality of using metasurfaces as an imaging platform. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement11Ysciescopu

Extremely broadband topological surface states in a photonic topological metamaterials

Metamaterials, artificially engineered materials consisting of subwavelength unit cell, have shown potentials in light manipulation with their extraordinary optical properties. Especially, topological metamaterials possessing topologically protected surface states enable extremely robust control of light. Here, we demonstrate extremely broadband topological phase in a photonic topological metamaterials with double helix structure. In particular topological surface states are observed for all the frequencies below a certain cut-off, originating from a double Weyl point at zero frequency. The extreme bandwidth and robustness of the photonic topological metamaterial are beneficial for practical applications such as one-way waveguide and photonic integrated systems but also advantageous in design and fabrication since the only necessary condition is to satisfy the effective hyperbolic and chiral properties, without entailing strict periodic arrangement