White light, which contains polychromic visible lights, affects the rhythm of organisms and has the potential for advanced applications of lighting, display, and communication. Compared

White light, which contains polychromic visible lights, affects the rhythm of organisms and has the potential for advanced applications of lighting, display, and communication. Compared with traditional incandescent bulbs and inorganic diodes, pure organic materials are superior in terms of better compatibility, flexibility, structural diversity and environmental friendliness. In the past few years, polychromic emission has been obtained based on organic aggregates, which provides a platform to achieve white-light emission. Several white-light emitters are sporadically reported, but the underlying mechanistic picture is still not fully established. Based on these considerations, this review will focus on the single-component and multi-component strategies to achieve efficient white-light emission from pure organic aggregates. Thereinto, single-component strategy is introduced from four parts: dual fluorescence, fluorescence and phosphorescence, dual phosphorescence with anti-Kasha’s behavior, and clusteroluminescence. Meanwhile, doping, supramolecular assembly, and cocrystallization are summarized as strategies for multi-component systems. Beyond the construction strategies of white-light emitters, their advanced representative applications, such as organic light-emitting diodes, white luminescent dyes, circularly polarized luminescence, and encryption, are also prospected. It is expected that this review will draw a comprehensive picture of white-light emission from organic aggregates as well as their emerging applicationsshow less

We designed a tunable wavelength-selective quasi-resonant cavity enhanced photodetector (QRCE-PD) based on high-contrast subwavelength grating (SWG). According to simulation results, it

We designed a tunable wavelength-selective quasi-resonant cavity enhanced photodetector (QRCE-PD) based on high-contrast subwavelength grating (SWG). According to simulation results, its peak quantum efficiency is 93.2%, 3-dB bandwidth is 33.5 GHz, spectral linewidth is 0.12nm, and wavelength-tuning range is 28 nm (1536 nm–1564 nm). The QRCE-PD contains a tunable Fabry-Perot filtering cavity (FPC), a symmetrical SWG deflection reflector (SSWG-DR) and a built-in p-i-n photodiode. The FPC and the SSWG-DR form an equivalent multi-region F-P cavity together by multiple mutual mirroring, which makes the QRCE-PD a multi-region resonant cavity enhanced photodetector. But QRCE-PD relies on the multiple-pass absorption enhanced effect to achieve high quantum efficiency, rather than the resonant cavity enhanced effect. This new photodetector structure is significant for the application in the dense wavelength division multiplexing (DWDM) systems. show less

When two synchronized laser beams illuminate the inner surface of bulk lithium niobate crystals with magnesium doping (5% /mol ) under the condition of total reflection, the semi-degene

When two synchronized laser beams illuminate the inner surface of bulk lithium niobate crystals with magnesium doping (5% /mol ) under the condition of total reflection, the semi-degenerate four wave mixing (FWM) generates. On this basis, the research on more sophisticated frequency conversion process on the interface of nonlinear crystal have been taken. The generation mechanism is associated with the scattering light of the fundamental waves reflected on the inner surface of nonlinear crystal. Analysis of phase matching mechanism confirms that the FWM is stimulated by third-order nonlinear susceptibilities of nonlinear material. Theoretically calculated and experimentally measured corresponding data have been presented in this article. These results are expected to provide new inspiration for further experimental and theoretical research on frequency conversion in nonlinear crystals.show less

The hole injection capability is essentially important for GaN-based vertical cavity surface emitting lasers (VCSELs) to enhance the laser power. In this work, we propose GaN-based VCSE

The hole injection capability is essentially important for GaN-based vertical cavity surface emitting lasers (VCSELs) to enhance the laser power. In this work, we propose GaN-based VCSELs with p-AlGaN/p-GaN structure as the p-type hole supplier to facilitate the hole injection. The p-AlGaN/p-GaN heterojunction is able to store the electric field and thus can moderately adjust the drift velocity and the kinetic energy for holes, which can improve the thermionic emission process for holes to travel across the p-type electron blocking layer (p-EBL). Besides, the valence band barrier height in the p-EBL can be reduced as a result of usage of the p-AlGaN layer. Therefore, the better stimulated radiative recombination rate and the increased laser power are obtained, thus enhancing the 3dB frequency bandwidth. Moreover, we also investigate the impact of p-AlGaN/p-GaN structure with various AlN compositions in the p-AlGaN layer on the hole injection capability, the laser power and the 3dB frequency bandwidth.show less