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Light-emitting diodes (LEDs) are widely used as next-generation light sources because of their various advantages. However, their luminous efficiency is remarkably low at the green-emission wavelength. The luminous efficiencies of InGaN/GaN quantum wells (QWs) significantly decrease with increasing indium content in the green wavelength region, mainly owing to the quantum-confined Stark effect (QCSE). This green gap problem can be solved using QWs grown on semi-polar GaN substrates, such as the {11–22} planes, to reduce the QCSE. We propose that the use of surface plasmons (SPs) is a promising way to improve the light emission efficiency of light-emitting materials such as InGaN/GaN QWs. SP resonance increases the spontaneous emission rates of the excited states, causes a relative reduction in non-radiative relaxation, and ultimately increases the internal quantum efficiencies. In this study, the light emissions of InGaN/GaN QWs grown on polar and semi-polar GaN were investigated using micro-photoluminescence (PL). We successfully enhanced the light emission of semi-polar GaN via SP resonance. The PL peak intensities and wavelengths were mapped and compared to determine the underlying mechanisms. We also measured the emission lifetimes by time-resolved PL and interpreted the detailed mechanism of SP-enhanced emissions. It was found that SP resonances can control not only the emission efficiency but also the exciton dynamics, such as exciton localization effects, QCSE screening, and defect level saturation. We conclude that the green gap problem can be solved by SP-enhanced light emission in semipolar InGaN/GaN.

This study investigates the optical properties of diffraction gratings using localized surface plasmon resonance (LSPR) with metal nano-hemispheres. We fabricated metal nano-hemisphere gratings (MNHGS) with Ga, Ag, and Au and examined their wavelength-selective diffraction properties. Our findings show that these gratings exhibit peak diffraction efficiencies at 300 nm, 500 nm, and 570 nm, respectively, corresponding to the LSPR wavelengths of each metal. The MNHGs were created through thermal nanoimprint and metal deposition, followed by annealing. The experimental and simulation results confirmed that the MNHGs selectively diffract light at their resonance wavelengths. Applying these findings to third-order nonlinear laser spectroscopy (MPT-TG method) enhances measurement sensitivity by reducing background noise through the selective diffraction of pump light while transmitting probe light. This innovation promises a highly sensitive method for observing subtle optical phenomena, enhancing the capabilities of nonlinear laser spectroscopy. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the surface plasmon characteristics of periodic silver nanodisk structures fabricated on a dielectric thin-film spacer layer on a Ag mirror substrate (NanoDisk on Mirror: NDoM) through finite difference time domain (FDTD) simulations and experiments involving actual sample fabrication. Through FDTD simulations, it was confirmed that the NDoM structure exhibits two sharp peaks in the visible range, and by adjusting the thickness of the spacer layer and the size of the nanodisk structure, sharp peaks can be obtained across the entire visible range. Additionally, we fabricated the NDoM structure using electron beam lithography (EBL) and experimentally confirmed that the obtained peaks matched the simulation results. Furthermore, we discovered that applying annealing at an appropriate temperature to the fabricated structure enables the adjustment of the resonance peak wavelength and enhances the scattering intensity by approximately five times. This enhancement is believed to result from changes in the shape and size of the nanodisk structure, as well as a reduction in grain boundaries in the metal crystal due to annealing. These results have the potential to contribute to technological advancements in various application fields, such as optical sensing and emission enhancement. [ABSTRACT FROM AUTHOR]

The optimal treatment strategy of high surgical risk patients with multivessel coronary artery disease (CAD) and functional mitral regurgitation (MR) remains controversial. We present two cases in which two-stage hybrid treatment with prior transcatheter mitral valve edge-to-edge repair (TEER) followed by off-pump coronary artery bypass grafting (OPCAB) was successfully performed in patients with CAD and functional ischemic MR. In both cases, the patient showed good hemodynamic stability during OPCAB without an increase in MR. A two-stage hybrid strategy with prior TEER followed by OPCAB may be an ideal treatment option for high surgical risk patients with multivessel CAD and functional ischemic MR. To recognize the effectiveness of a two-stage hybrid approach with transcatheter edge-to-edge repair and off-pump coronary artery bypass grafting in high surgical risk patients with multivessel coronary artery disease and functional mitral regurgitation. [ABSTRACT FROM AUTHOR]

This paper delves into the strategic design and optimization of silver (Ag) nanostructured arrays within plasmonic metamaterials, targeting the enhancement of imaging sensitivity. Leveraging Finite-Difference Time-Domain (FDTD) simulations, our research rigorously compares various Ag nanostructured geometries, including nanospheres, nanocones, nanodisks, and nanocubes. The aim is to pinpoint configurations that significantly enhance electric field localization on the surfaces of nanostructures, a pivotal factor. The nanocube array exhibits superior field enhancement, particularly in narrow nanogaps, suggesting its suitability for high-sensitivity applications. Further exploration into nanocube arrays reveals the crucial role of nanogap size and spacer layer thickness in tuning the optical properties through the manipulation of Fabry–Pérot and mirror image modes in metal–insulator–metal (MIM) structures. By presenting a thorough analysis of these nanostructured arrays, the study not only contributes to our understanding of the fundamental principles governing plasmonic metamaterials but also provides a solid foundation for future innovation in highly sensitive imaging applications. It underscores the importance of nanostructure design and optimization in achieving significant improvements in the performance of plasmonic devices, marking a pivotal step forward in the field of nanophotonics and its application to sensitive imaging technologies. [ABSTRACT FROM AUTHOR]