Giant infrared bulk photovoltaic effect in tellurene for broad-spectrum neuromodulation
巨型红外体光伏效应在硒烯中的宽谱神经调制
Authors: Zhen Wang, Chunhua Tan, Meng Peng, Yiye Yu, Fang Zhong, Peng Wang, Ting He, Yang Wang, Zhenhan Zhang, Runzhang Xie, Fang Wang, Shuijin He, Peng Zhou, Weida Hu
Date: 27 September 2024
Abstract:
Given the surpassing of the Shockley-Quiesser efficiency limit in conventional p-n junction photovoltaic effect, bulk photovoltaic effect (BPVE) has garnered significant research interest. However, the BPVE primarily focuses on a narrow wavelength range, limiting its potential applications. Here we report a giant infrared bulk photovoltaic effect in tellurene (Te) for broad-spectrum neuromodulation. The generated photocurrent in uniformly illuminated Te excludes other photoelectric effects and is attributed to the BPVE. The bulk photovoltaic wavelength in Te spans a wide range from the ultraviolet (390 nm) to the mid-infrared (3.8 µm). Moreover, the photocurrent density of 70.4 A cm−2 under infrared light simulation outperforms that in previous ultraviolet and visible semiconductors as well as infrared semimetals. Te attached to the dendrites or somata of the cortical neurons successfully elicits action potentials under broad-spectrum light irradiation. This work lays the foundation for the further development of infrared BPVE in narrow bandgap materials.
Keywords: bulk photovoltaic effect, tellurene, neuromodulation, photocurrent density, infrared light
Link: https://www.nature.com/articles/s41377-024-01640-wHigh discrimination ratio, broadband circularly polarized light photodetector using dielectric achiral nanostructures
高分辨率宽带圆偏振光光电探测器使用介电非手性纳米结构
Authors: Guanyu Zhang, Xiaying Lyu, Yulu Qin, Yaolong Li, Zipu Fan, Xianghan Meng, Yuqing Cheng, Zini Cao, Yixuan Xu, Dong Sun, Yunan Gao, Qihuang Gong, Guowei Lyu
Date: 27 September 2024
Abstract:
The on-chip measurement of polarization states plays an increasingly crucial role in modern sensing and imaging applications. While high-performance monolithic linearly polarized photodetectors have been extensively studied, integrated circularly polarized light (CPL) photodetectors are still hindered by inadequate discrimination capability. This study presents a broadband CPL photodetector utilizing achiral all-dielectric nanostructures, achieving an impressive discrimination ratio of ~107 at a wavelength of 405 nm. Our device shows outstanding CPL discrimination capability across the visible band without requiring intensity calibration. It functions based on the CPL-dependent near-field modes within achiral structures: under left or right CPL illumination, distinct near-field modes are excited, resulting in asymmetric irradiation of the two electrodes and generating a photovoltage with directions determined by the chirality of the incident light field. The proposed design strategy facilitates ultra-compact CPL detection across diverse materials, structures, and spectral ranges, presenting a novel avenue for achieving high-performance monolithic CPL detection.
Keywords: circularly polarized light, photodetector, dielectric nanostructures, discrimination ratio, sensing
Link: https://www.nature.com/articles/s41377-024-01634-8Continuous evolution of Fermi arcs in a minimal ideal photonic Weyl medium
Fermi弧在最小理想光子Weyl介质中的连续演变
Authors: Yachao Liu, Mingwei Wang, Yongqing Huang, Guo Ping Wang, Shuang Zhang
Date: 27 September 2024
Abstract:
Propagation properties of electromagnetic waves in an optical medium are mainly determined by the contour of equal-frequency states in ({\boldsymbol{k}})-space. In photonic Weyl media, the topological surface waves lead to a unique open arc of the equal-frequency contour, called the Fermi arc. However, for most realistic Weyl systems, the shape of Fermi arcs is fixed due to the constant impedance of the surrounding medium, making it difficult to manipulate the surface wave. Here we demonstrate that by adjusting the thickness of the air layer sandwiched between two photonic Weyl media, the shape of the Fermi arc can be continuously changed from convex to concave. Moreover, we show that the concave Fermi-arc waves can be used to achieve topologically protected electromagnetic pulling forces over a broad range of angles in the air layer. Our finding offers a generally applicable strategy to shape the Fermi arc in photonic Weyl media.
Keywords: Fermi arc, photonic Weyl media, electromagnetic waves, topological surface waves, air layer
Link: https://www.nature.com/articles/s41377-024-01632-wLaser solid-phase synthesis of graphene shell-encapsulated high-entropy alloy nanoparticles
激光固相合成包覆石墨烯的高熵合金纳米颗粒
Authors: Yuxiang Liu, Jianghuai Yuan, Jiantao Zhou, Kewen Pan, Ran Zhang, Rongxia Zhao, Lin Li, Yihe Huang, Zhu Liu
Date: 26 September 2024
Abstract:
Rapid synthesis of high-entropy alloy nanoparticles (HEA NPs) offers new opportunities to develop functional materials in widespread applications. Although some methods have successfully produced HEA NPs, these methods generally require rigorous conditions such as high pressure, high temperature, restricted atmosphere, and limited substrates, which impede practical viability. In this work, we report laser solid-phase synthesis of CrMnFeCoNi nanoparticles by laser irradiation of mixed metal precursors on a laser-induced graphene (LIG) support with a 3D porous structure. The CrMnFeCoNi nanoparticles are embraced by several graphene layers, forming graphene shell-encapsulated HEA nanoparticles. The mechanisms of the laser solid-phase synthesis of HEA NPs on LIG supports are investigated through theoretical simulation and experimental observations, considering mixed metal precursor adsorption, thermal decomposition, reduction through electrons from laser-induced thermionic emission, and liquid beads splitting. The production rate reaches up to 30 g/h under the current laser setup. The laser-synthesized graphene shell-encapsulated CrMnFeCoNi NPs loaded on LIG-coated carbon paper are used directly as 3D binder-free integrated electrodes and exhibited excellent electrocatalytic activity towards oxygen evolution reaction with an overpotential of 293 mV at the current density of 10 mA/cm² and exceptional stability over 428 h in alkaline media, outperforming the commercial RuO2 catalyst and the relevant catalysts reported by other methods. This work also demonstrates the versatility of this technique through the successful synthesis of CrMnFeCoNi oxide, sulfide, and phosphide nanoparticles.
Keywords: high-entropy alloy nanoparticles, graphene, electrocatalysis, oxygen evolution, laser synthesis
Link: https://www.nature.com/articles/s41377-024-01614-yUltrahigh-resolution, high-fidelity quantum dot pixels patterned by dielectric electrophoretic deposition
超高分辨率、高保真度量子点像素通过介电电泳沉积图案化
Authors: Chengzhao Luo, Yanhui Ding, Zhenwei Ren, Chenglong Wu, Yonghuan Huo, Xin Zhou, Zhiyong Zheng, Xinwen Wang, Yu Chen
Date: 26 September 2024
Abstract:
The high pixel resolution is emerging as one of the key parameters for the next-generation displays. Despite the development of various quantum dot (QD) patterning techniques, achieving ultrahigh-resolution (>10,000 pixels per inch (PPI)) and high-fidelity QD patterns is still a tough challenge that needs to be addressed urgently. Here, we propose a novel and effective approach of orthogonal electric field-induced template-assisted dielectric electrophoretic deposition to successfully achieve one of the highest pixel resolutions of 23090 (PPI) with a high fidelity of up to 99%. Meanwhile, the proposed strategy is compatible with the preparation of QD pixels based on perovskite CsPbBr3 and conventional CdSe QDs, exhibiting a wide applicability for QD pixel fabrication. Notably, we further demonstrate the great value of our approach to achieve efficiently electroluminescent QD pixels with a peak external quantum efficiency of 16.5%. Consequently, this work provides a general approach for realizing ultrahigh-resolution and high-fidelity patterns based on various QDs and a novel method for fabricating QD-patterned devices with high performance.
Keywords: quantum dots, pixel resolution, electrophoretic deposition, electroluminescence, display technology
Link: https://www.nature.com/articles/s41377-024-01601-3One-dimensional photonic crystal enhancing spin-to-orbital angular momentum conversion for single-particle tracking
一维光子晶体增强单粒子追踪中的自旋到轨道角动量转换
Authors: Mingchuan Huang, Qiankun Chen, Yang Liu, Chi Zhang, Rongjin Zhang, Junhua Yuan, Douguo Zhang
Date: 26 September 2024
Abstract:
Single-particle tracking (SPT) is an immensely valuable technique for studying various processes in life sciences and physics. It helps researchers understand the positions, paths, and interactions of single objects in highly dynamic systems or those requiring extended imaging. Here, we propose an all-dielectric one-dimensional photonic crystal (1D PC) that enhances spin-to-orbital angular momentum conversion for three-dimensional (3D) SPTs. This well-designed 1D PC can function as a substrate for optical microscopy. We introduce this effect into the interferometric scattering (iSCAT) technique, resulting in a double-helix point spread function (DH-PSF). The DH-PSF provides more uniform Fisher information for 3D position estimation than conventional microscopy PSFs, encoding the axial position of a single particle in the angular orientation of DH-PSF lobes. This approach addresses the challenge of iSCAT in 3D SPT, as DH-PSF iSCAT avoids multiple contrast inversions when a single particle moves axially. The DH-PSF iSCAT technique was used to record the 3D trajectory of a microbead, facilitating precise analysis of motor dynamics.
Keywords: single-particle tracking, photonic crystal, angular momentum, optical microscopy, interferometric scattering
Link: https://www.nature.com/articles/s41377-024-01623-xBright compact ultrabroadband source by orthogonal laser-sustained plasma
通过正交激光维持的等离子体实现明亮紧凑的超宽带光源
Authors: Zhaojiang Shi, Shichao Yang, He Hu, Haodong Lei, Zhaohua Yang, Xia Yu
Date: 26 September 2024
Abstract:
Laser-sustained plasma (LSP) sources featuring high brightness and broadband spectral coverage are powerful in various scientific and industrial applications. However, the fundamental limit of low conversion efficiency constrains the compactness and widespread application of such broadband light sources. In this paper, we propose an innovative orthogonal LSP to overcome this limitation. Driven by enhanced conversion efficiency from absorbed laser power to ultraviolet (UV) emission, a compact broadband source (250–1650 nm) with UV spectral radiance exceeding 210 mW/(mm²·sr·nm) is achieved with >100 W pump laser. We report a conceptual advance that the orthogonal design eliminates the influence of the negative lensing effect on laser power density. Experimental results demonstrate a bright compact UV-VIS-NIR source with negligible thermal loss and the highest conversion efficiency reported. The proposed ultrabroadband source significantly enhances the contrast-to-noise ratio (CNR) in spectral single-pixel imaging. This work presents a compact broadband source combining superior conversion efficiency and unprecedented brightness, essential for high-speed inspection and spectroscopy applications.
Keywords: laser-sustained plasma, ultrabroadband source, conversion efficiency, spectral radiance, imaging
Link: https://www.nature.com/articles/s41377-024-01602-2Dielectric metamaterials with effective self-duality and full-polarization omnidirectional Brewster effect
具有有效自对称和全极化全方位布鲁斯特效应的介电超材料
Authors: Hao Luo, Jie Luo, Zhihui Zhang, Chao Wu, Quan Li, Wei Liu, Ruwen Peng, Mu Wang, Hongqiang Li, Yun Lai
Date: 20 September 2024
Abstract:
Conventional dielectric solid materials, both natural and artificial, lack electromagnetic self-duality and thus require additional coatings for impedance matching with free space. Here, we present a class of dielectric metamaterials that are effectively self-dual and vacuum-like, exhibiting full-polarization omnidirectional impedance matching as an unusual Brewster effect extended across all incident angles and polarizations. With both birefringence and reflection eliminated regardless of wavefront and polarization, these anisotropic metamaterials establish electromagnetic equivalence with “stretched free space” in transformation optics, substantiated through full-wave simulations and microwave experiments. Our findings open a practical pathway for realizing unprecedented polarization-independence and omnidirectional impedance-matching characteristics in pure dielectric solids.
Keywords: dielectric metamaterials, self-duality, Brewster effect, impedance matching, transformation optics
Link: https://www.nature.com/articles/s41377-024-01605-zSuppressed concentration quenching and tunable photoluminescence in Eu2+-activated Rb3Y(PO4)2 phosphors for full-spectrum lighting
抑制浓度猝灭和可调光致发光在Eu2+激活的Rb3Y(PO4)2荧光粉中的全谱照明应用
Authors: Ming Zhao, Yeping Ge, Yurong Li, Xiaoyan Song, Zhiguo Xia, Xinping Zhang
Date: 20 September 2024
Abstract:
Highly efficient inorganic phosphors are desirable for light-emitting diode sources, and increasing the doping concentration of activators is a common approach to enhance photoluminescence quantum yield (PLQY). However, concentration quenching poses a significant challenge for improving PLQY. We propose a design principle by separating activators and prolonging their distance in Eu2+-activated Rb3Y(PO4)2 phosphors to inhibit concentration quenching, where different quenching rates are controlled by the Eu distribution at various crystallographic sites. The blue-violet-emitting Rb3Y(PO4)2:xEu (x = 0.1%–15%) phosphors exhibit rapid luminescence quenching with an optimum external PLQY of 10%. Interestingly, as the Eu concentration exceeds 20%, Eu2+ occupies Rb1 and Y sites with larger interionic distances, leading to green emission with suppressed concentration quenching and an improved external PLQY of 41%. This study provides a unique design perspective for enhancing the efficiency of Eu2+-activated phosphors for high-performance full-spectrum lighting.
Keywords: phosphors, photoluminescence, concentration quenching, Eu2+ activation, lighting
Link: https://www.nature.com/articles/s41377-024-01607-xMeasuring, processing, and generating partially coherent light with self-configuring optics
测量、处理和生成具有自配置光学的部分相干光
Authors: Charles Roques-Carmes, Shanhui Fan, David A. B. Miller
Date: 20 September 2024
Abstract:
Optical phenomena often exhibit some degree of partial coherence across their degrees of freedom. Partial coherence is particularly significant in multimodal systems, where correlations between spatial, polarization, and spectral degrees can lead to intriguing phenomena and be utilized for advanced imaging and sensing. Here, we present a universal method for analyzing, processing, and generating spatially partially coherent light in multimode systems through self-configuring optical networks. This method relies on cascaded self-configuring layers with sequentially optimized power outputs. Once optimized, the network separates input light into its mutually incoherent components, formally equivalent to diagonalizing the input density matrix. We illustrate our method through numerical simulations of Mach-Zehnder interferometer arrays, demonstrating its capability for partially coherent light sensing, generating multimode partially coherent light, and unscrambling quantum optical mixtures. This work paves the way for self-configuring photonic devices that can automatically learn optimal modal representations of partially coherent light fields.
Keywords: partially coherent light, self-configuring optics, multimodal systems, quantum optics, imaging
Link: https://www.nature.com/articles/s41377-024-01622-y
