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    Vol. 13 Issue 9 2024

      News & Views

    • Tianyu Zhao,Ming Lei
      Vol. 13, Issue 9, Pages: 1693-1695(2024) DOI: 10.1038/s41377-024-01505-2
      Abstract:Parallel acquisition-readout structured-illumination microscopy (PAR-SIM) was designed for high-speed raw data acquisition. By utilizing an xy-scan galvo mirror set, the raw data is projected onto different areas of the camera, enabling a fundamentally stupendous information spatial-temporal flux.  
        
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    • Yan Li,Shin-Tson Wu
      Vol. 13, Issue 9, Pages: 1696-1697(2024) DOI: 10.1038/s41377-024-01538-7
      Abstract:A versatile and tunable vectorial holography is demonstrated based on single-layer single-material liquid crystal superstructures. This novel approach advances the process from scalar to vectorial holography, opening new opportunities for advanced cryptography, super-resolution imaging, and many other tunable photonic applications.  
        
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    • Jiazhe Ma,Zhongqiang Yang
      Vol. 13, Issue 9, Pages: 1698-1700(2024) DOI: 10.1038/s41377-024-01549-4
      Abstract:Chiral liquid crystal elastomers, as soft photonic materials, enable dynamic omnidirectional tuning of circularly polarized reflection wavelength and function as an effective medium for full-color circularly polarized luminescence, showing promise for advanced photonic applications.  
        
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    • Fazilah Nothlawala,Andrew Forbes
      Vol. 13, Issue 9, Pages: 1701-1703(2024) DOI: 10.1038/s41377-024-01550-x
      Abstract:High-dimensional quantum states are known to offer advantages over their two-dimensional qubit counterparts, but their preparation and manipulation has been bulky and cumbersome. Now, quantum state control has been demonstrated on-chip with a ~1 μm2 footprint and nm-scale features, producing up to eight-dimensional quantum states and ushering in a new route to large quantum information encoding on a small footprint.  
        
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      Light People

    • Ruidong Xia,Ying Hu
      Vol. 13, Issue 9, Pages: 1704-1719(2024) DOI: 10.1038/s41377-024-01527-w
      Abstract:The invention of organic light emitting diodes (LEDs) led to enormous excitement in both academe and industry in the late 1980's. Flexibility, large area solution processability, roll-to-roll printing, low cost, and environmentally friendly are some of the advantages of organic semiconductor materials, which brought a new horizon for optoelectronics. Together with the achievement of organic solar cells, transistors, lasers, and amplifiers, this has demonstrated potential applications of organic semiconductors in displays, lighting, solar energy generation, electronics, sensing and imaging, and many aspects of photonics. In an enlightened conversation with Light: Science & Applications, Prof. Donal Bradley (FRS), a pioneer in the field, shared his deep insights on past, current, and future exciting developments of organic optoelectronic materials and devices. In particular, he expressed his opinion on the hot topics related to organic optoelectronics research and application, such as the relationship between organic and inorganic semiconductors and the challenge of electrically pumped organic lasers. As a successful scientist, Donal has also been co-founder of several organic optoelectronics innovation companies and research centers and a long-term academic administrator serving as a Head of Department, Centre Director, and Vice-Rector for Research at Imperial College, Head of the Mathematical, Physical, and Life Sciences Division at the University of Oxford, Vice-President for Research at King Abdullah University of Science and Technology and now Vice-President for Research and Innovation at NEOM U and Executive Director of the NEOM Education, Research and Innovation Foundation. Through this interview, we also explore the major roles and events in Donal's career experience from the invention of the first conjugated polymer LED in the world to the set-up of entrepreneurial companies, from Cambridge to Sheffield, Imperial College, and Oxford, from the UK to overseas, and from the establishment of the Centre for Plastic Electronics in Imperial College to the set-up of the Oxford Suzhou Centre for Advanced Research (OSCAR). Before the end of the conversation, he also shares his interesting story of identifying a new species of Sea Bream, Acanthopagrus oconnorae (Bev Bradley's Bream), named after his mother and wife, while fishing in the Red Sea.  
        
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      Review

    • Naseer Muhammad,Zhaoxian Su,Qiang Jiang,Yongtian Wang,Lingling Huang
      Vol. 13, Issue 9, Pages: 1720-1740(2024) DOI: 10.1038/s41377-024-01548-5
      Abstract:Non-radiative optical modes attracted enormous attention in optics due to strong light confinement and giant Q-factor at its spectral position. The destructive interference of multipoles leads to zero net-radiation and strong field trapping. Such radiationless states disappear in the far-field, localize enhanced near-field and can be excited in nano-structures. On the other hand, the optical modes turn out to be completely confined due to no losses at discrete point in the radiation continuum, such states result in infinite Q-factor and lifetime. The radiationless states provide a suitable platform for enhanced light matter interaction, lasing, and boost nonlinear processes at the state regime. These modes are widely investigated in different material configurations for various applications in both linear and nonlinear metasurfaces which are briefly discussed in this review.  
        
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      Original Articles

    • Wei Ren,Xichuan Ge,Meiqi Li,Jing Sun,Shiyi Li,Shu Gao,Chunyan Shan,Baoxiang Gao,Peng Xi
      Vol. 13, Issue 9, Pages: 1741-1756(2024) DOI: 10.1038/s41377-024-01463-9
      Abstract:Mitochondria are crucial organelles closely associated with cellular metabolism and function. Mitochondrial DNA (mtDNA) encodes a variety of transcripts and proteins essential for cellular function. However, the interaction between the inner membrane (IM) and mtDNA remains elusive due to the limitations in spatiotemporal resolution offered by conventional microscopy and the absence of suitable in vivo probes specifically targeting the IM. Here, we have developed a novel fluorescence probe called HBmito Crimson, characterized by exceptional photostability, fluorogenicity within lipid membranes, and low saturation power. We successfully achieved over 500 frames of low-power stimulated emission depletion microscopy (STED) imaging to visualize the IM dynamics, with a spatial resolution of 40 nm. By utilizing dual-color imaging of the IM and mtDNA, it has been uncovered that mtDNA tends to habitat at mitochondrial tips or branch points, exhibiting an overall spatially uniform distribution. Notably, the dynamics of mitochondria are intricately associated with the positioning of mtDNA, and fusion consistently occurs in close proximity to mtDNA to minimize pressure during cristae remodeling. In healthy cells, > 66% of the mitochondria are Class Ⅲ (i.e., mitochondria > 5 μm or with > 12 cristae), while it dropped to < 18% in ferroptosis. Mitochondrial dynamics, orchestrated by cristae remodeling, foster the even distribution of mtDNA. Conversely, in conditions of apoptosis and ferroptosis where the cristae structure is compromised, mtDNA distribution becomes irregular. These findings, achieved with unprecedented spatiotemporal resolution, reveal the intricate interplay between cristae and mtDNA and provide insights into the driving forces behind mtDNA distribution.  
        
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    • Yifei Qi,Longqun Ni,Zhenyu Ye,Jiaojiao Zhang,Xingyu Bao,Pan Wang,Yunjiang Rao,Ernesto P. Raposo,Anderson S. L. Gomes,Zinan Wang
      Vol. 13, Issue 9, Pages: 1757-1765(2024) DOI: 10.1038/s41377-024-01475-5
      Abstract:Spin glass theory, as a paradigm for describing disordered magnetic systems, constitutes a prominent subject of study within statistical physics. Replica symmetry breaking (RSB), as one of the pivotal concepts for the understanding of spin glass theory, means that under identical conditions, disordered systems can yield distinct states with nontrivial correlations. Random fiber laser (RFL) based on Rayleigh scattering (RS) is a complex disordered system, owing to the disorder and stochasticity of RS. In this work, for the first time, a precise theoretical model is elaborated for studying the photonic phase transition via the platform of RS-based RFL, in which we clearly reveal that, apart from the pump power, the photon phase variation in RFL is also an analogy to the temperature term in spin-glass phase transition, leading to a novel insight into the intrinsic mechanisms of photonic phase transition. In addition, based on this model and real-time high-fidelity detection spectral evolution, we theoretically predict and experimentally observe the mode-asymmetric characteristics of photonic phase transition in RS-based RFL. This finding contributes to a deeper understanding of the photonic RSB regime and the dynamics of RS-based RFL.  
        
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    • Pengming Song,Ruihai Wang,Lars Loetgering,Jia Liu,Peter Vouras,Yujin Lee,Shaowei Jiang,Bin Feng,Andrew Maiden,Changhuei Yang,Guoan Zheng
      Vol. 13, Issue 9, Pages: 1766-1778(2024) DOI: 10.1038/s41377-024-01510-5
      Abstract:Synthetic aperture radar (SAR) utilizes an aircraft-carried antenna to emit electromagnetic pulses and detect the returning echoes. As the aircraft travels across a designated area, it synthesizes a large virtual aperture to improve image resolution. Inspired by SAR, we introduce synthetic aperture ptycho-endoscopy (SAPE) for micro-endoscopic imaging beyond the diffraction limit. SAPE operates by hand-holding a lensless fiber bundle tip to record coherent diffraction patterns from specimens. The fiber cores at the distal tip modulate the diffracted wavefield within a confined area, emulating the role of the 'airborne antenna' in SAR. The handheld operation introduces positional shifts to the tip, analogous to the aircraft's movement. These shifts facilitate the acquisition of a ptychogram and synthesize a large virtual aperture extending beyond the bundle's physical limit. We mitigate the influences of hand motion and fiber bending through a low-rank spatiotemporal decomposition of the bundle's modulation profile. Our tests demonstrate the ability to resolve a 548-nm linewidth on a resolution target. The achieved space-bandwidth product is ~1.1 million effective pixels, representing a 36-fold increase compared to that of the original fiber bundle. Furthermore, SAPE's refocusing capability enables imaging over an extended depth of field exceeding 2 cm. The aperture synthesizing process in SAPE surpasses the diffraction limit set by the probe's maximum collection angle, opening new opportunities for both fiber-based and distal-chip endoscopy in applications such as medical diagnostics and industrial inspection.  
        
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    • Yuan Liu,Hongwei Zhou,Linhan Lin,Hong-Bo Sun
      Vol. 13, Issue 9, Pages: 1779-1788(2024) DOI: 10.1038/s41377-024-01508-z
      Abstract:The emitter-cavity strong coupling manifests crucial significance for exploiting quantum technology, especially in the scale of individual emitters. However, due to the small light-matter interaction cross-section, the single emitter-cavity strong coupling has been limited by its harsh requirement on the quality factor of the cavity and the local density of optical states. Herein, we present a strategy termed waveguide-assisted energy quantum transfer (WEQT) to improve the single emitter-cavity coupling strength by extending the interaction cross-section. Multiple ancillary emitters are optically linked by a waveguide, providing an indirect coupling channel to transfer the energy quantum between target emitter and cavity. An enhancement factor of coupling strength $ \widetilde{g}/g \gt 10 $ can be easily achieved, which dramatically release the rigorous design of cavity. As an extension of concept, we further show that the ancillae can be used as controlling bits for a photon gate, opening up new degrees of freedom in quantum manipulation.  
        
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    • Wei Liu,Si Ran Wang,Jun Yan Dai,Lei Zhang,Qiao Chen,Qiang Cheng,Tie Jun Cui
      Vol. 13, Issue 9, Pages: 1789-1800(2024) DOI: 10.1038/s41377-024-01513-2
      Abstract:Independent controls of various properties of electromagnetic (EM) waves are crucially required in a wide range of applications. Programmable metasurface is a promising candidate to provide an advanced platform for manipulating EM waves. Here, we propose an approach that can arbitrarily control the polarization direction and phases of reflected waves in linear and nonlinear ways using a stacked programmable metasurface. Further, we extend the space-time-coding theory to incorporate the dimension of polarization, which provides an extra degree of freedom for manipulating EM waves. As proof-of-principle application examples, we consider polarization rotation, phase manipulation, and beam steering at linear and nonlinear frequencies. For validation, we design, fabricate, and measure a metasurface sample. The experimental results show good agreement with theoretical predictions and simulations. The proposed approach has a wide range of applications in various areas, such as imaging, data storage, and wireless communication.  
        
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    • Zhe Zhou,Yueyue Wu,Keyuan Pan,Duoyi Zhu,Zifan Li,Shiqi Yan,Qian Xin,Qiye Wang,Xinkai Qian,Fei Xiu,Wei Huang,Juqing Liu
      Vol. 13, Issue 9, Pages: 1801-1808(2024) DOI: 10.1038/s41377-024-01519-w
      Abstract:Crossbar resistive memory architectures enable high-capacity storage and neuromorphic computing, accurate retrieval of the stored information is a prerequisite during read operation. However, conventional electrical readout normally suffer from complicated process, inaccurate and destructive reading due to crosstalk effect from sneak path current. Here we report a memristive-photoconductive transduction (MPT) methodology for precise and nondestructive readout in a memristive crossbar array. The individual devices present dynamic filament form/fuse for resistance modulation under electric stimulation, which leads to photogenerated carrier transport for tunable photoconductive response under subsequently light pulse stimuli. This coherent signal transduction can be used to directly detect the memorized on/off states stored in each cell, and a prototype 4 * 4 crossbar memories has been constructed and validated for the fidelity of crosstalk-free readout in recall process.  
        
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    • Siyin Dong,Zhenghui Fan,Wei Wei,Shujie Tie,Ruihan Yuan,Bin Zhou,Ning Yang,Xiaojia Zheng,Liang Shen
      Vol. 13, Issue 9, Pages: 1809-1819(2024) DOI: 10.1038/s41377-024-01521-2
      Abstract:Quasi-two-dimensional (Q-2D) perovskite exhibits exceptional photoelectric properties and demonstrates reduced ion migration compared to 3D perovskite, making it a promising material for the fabrication of highly sensitive and stable X-ray detectors. However, achieving high-quality perovskite films with sufficient thickness for efficient X-ray absorption remains challenging. Herein, we present a novel approach to regulate the growth of Q-2D perovskite crystals in a mixed atmosphere comprising methylamine (CH3NH2, MA) and ammonia (NH3), resulting in the successful fabrication of high-quality films with a thickness of hundreds of micrometers. Subsequently, we build a heterojunction X-ray detector by incorporating the perovskite layer with titanium dioxide (TiO2). The precise regulation of perovskite crystal growth and the meticulous design of the device structure synergistically enhance the resistivity and carrier transport properties of the X-ray detector, resulting in an ultrahigh sensitivity (29721.4 μC Gyair−1 cm−2) for low-dimensional perovskite X-ray detectors and a low detection limit of 20.9 nGyair s−1. We have further demonstrated a flat panel X-ray imager (FPXI) showing a high spatial resolution of 3.6 lp mm−1 and outstanding X-ray imaging capability under low X-ray doses. This work presents an effective methodology for achieving high-performance Q-2D perovskite FPXIs that holds great promise for various applications in imaging technology.  
        
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    • Komron J. Shayegan,Jae S. Hwang,Bo Zhao,Aaswath P. Raman,Harry A. Atwater
      Vol. 13, Issue 9, Pages: 1820-1827(2024) DOI: 10.1038/s41377-024-01520-3
      Abstract:A body that violates Kirchhoff's law of thermal radiation exhibits an inequality in its spectral directional absorptivity and emissivity. Achieving such an inequality is of fundamental interest as well as a prerequisite for achieving thermodynamic limits in photonic energy conversion1 and radiative cooling2. Thus far, inequalities in the spectral directional emissivity and absorptivity have been limited to narrow spectral resonances3, or wavelengths well beyond the infrared regime4. Bridging the gap from basic demonstrations to practical applications requires control over a broad spectral range of the unequal spectral directional absorptivity and emissivity. In this work, we demonstrate broadband nonreciprocal thermal emissivity and absorptivity by measuring the thermal emissivity and absorptivity of gradient epsilon-near-zero InAs layers of subwavelength thicknesses (50 nm and 150 nm) with an external magnetic field. The effect occurs in a spectral range (12.5–16 μm) that overlaps with the infrared transparency window and is observed at moderate (1 T) magnetic fields.  
        
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    • Juntong Li,Yanping Ni,Xiaoli Zhao,Bin Wang,Chuang Xue,Zetong Bi,Cong Zhang,Yongjun Dong,Yanhong Tong,Qingxin Tang,Yichun Liu
      Vol. 13, Issue 9, Pages: 1828-1840(2024) DOI: 10.1038/s41377-024-01524-z
      Abstract:Vertically stacked all-organic active-matrix organic light-emitting diodes are promising candidates for high-quality skin-like displays due to their high aperture ratio, extreme mechanical flexibility, and low-temperature processing ability. However, these displays suffer from process interferences when interconnecting functional layers made of all-organic materials. To overcome this challenge, we present an innovative integration strategy called "discrete preparation-multilayer lamination" based on microelectronic processes. In this strategy, each functional layer was prepared separately on different substrates to avoid chemical and physical damage caused by process interferences. A single interconnect layer was introduced between each vertically stacked functional layer to ensure mechanical compatibility and interconnection. Compared to the previously reported layer-by-layer preparation method, the proposed method eliminates the need for tedious protection via barrier and pixel-defining layer processing steps. Additionally, based on active-matrix display, this strategy allows multiple pixels to collectively display a pattern of "1" with an aperture ratio of 83%. Moreover, the average mobility of full-photolithographic organic thin-film transistors was 1.04 cm2 V−1 s1, ensuring stable and uniform displays. This strategy forms the basis for the construction of vertically stacked active-matrix displays, which should facilitate the commercial development of skin-like displays in wearable electronics.  
        
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    • Bijie Bai,Xilin Yang,Tianyi Gan,Jingxi Li,Deniz Mengu,Mona Jarrahi,Aydogan Ozcan
      Vol. 13, Issue 9, Pages: 1841-1864(2024) DOI: 10.1038/s41377-024-01543-w
      Abstract:Diffractive deep neural networks (D2NNs) are composed of successive transmissive layers optimized using supervised deep learning to all-optically implement various computational tasks between an input and output field-of-view. Here, we present a pyramid-structured diffractive optical network design (which we term P-D2NN), optimized specifically for unidirectional image magnification and demagnification. In this design, the diffractive layers are pyramidally scaled in alignment with the direction of the image magnification or demagnification. This P-D2NN design creates high-fidelity magnified or demagnified images in only one direction, while inhibiting the image formation in the opposite direction—achieving the desired unidirectional imaging operation using a much smaller number of diffractive degrees of freedom within the optical processor volume. Furthermore, the P-D2NN design maintains its unidirectional image magnification/demagnification functionality across a large band of illumination wavelengths despite being trained with a single wavelength. We also designed a wavelength-multiplexed P-D2NN, where a unidirectional magnifier and a unidirectional demagnifier operate simultaneously in opposite directions, at two distinct illumination wavelengths. Furthermore, we demonstrate that by cascading multiple unidirectional P-D2NN modules, we can achieve higher magnification factors. The efficacy of the P-D2NN architecture was also validated experimentally using terahertz illumination, successfully matching our numerical simulations. P-D2NN offers a physics-inspired strategy for designing task-specific visual processors.  
        
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    • Minrui Lian,Changsong Gao,Zhenyuan Lin,Liuting Shan,Cong Chen,Yi Zou,Enping Cheng,Changfei Liu,Tailiang Guo,Wei Chen,Huipeng Chen
      Vol. 13, Issue 9, Pages: 1865-1877(2024) DOI: 10.1038/s41377-024-01516-z
      Abstract:Memristor-based physical reservoir computing holds significant potential for efficiently processing complex spatiotemporal data, which is crucial for advancing artificial intelligence. However, owing to the single physical node mapping characteristic of traditional memristor reservoir computing, it inevitably induces high repeatability of eigenvalues to a certain extent and significantly limits the efficiency and performance of memristor-based reservoir computing for complex tasks. Hence, this work firstly reports an artificial light-emitting synaptic (LES) device with dual photoelectric output for reservoir computing, and a reservoir system with mixed physical nodes is proposed. The system effectively transforms the input signal into two eigenvalue outputs using a mixed physical node reservoir comprising distinct physical quantities, namely optical output with nonlinear optical effects and electrical output with memory characteristics. Unlike previously reported memristor-based reservoir systems, which pursue rich reservoir states in one physical dimension, our mixed physical node reservoir system can obtain reservoir states in two physical dimensions with one input without increasing the number and types of devices. The recognition rate of the artificial light-emitting synaptic reservoir system can achieve 97.22% in MNIST recognition. Furthermore, the recognition task of multichannel images can be realized through the nonlinear mapping of the photoelectric dual reservoir, resulting in a recognition accuracy of 99.25%. The mixed physical node reservoir computing proposed in this work is promising for implementing the development of photoelectric mixed neural networks and material-algorithm collaborative design.  
        
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    • Yang Lu,Xu Zhao,Dongmei Yan,Yingqian Mi,Peng Sun,Xu Yan,Xiaomin Liu,Geyu Lu
      Vol. 13, Issue 9, Pages: 1878-1887(2024) DOI: 10.1038/s41377-024-01539-6
      Abstract:Chiral assemblies have become one of the most active research areas due to their versatility, playing an increasingly important role in bio-detection, imaging and therapy. In this work, chiral UCNPs/CuxOS@ZIF nanoprobes are prepared by encapsulating upconversion nanoparticles (UCNPs) and CuxOS nanoparticles (NPs) into zeolitic imidazolate framework-8 (ZIF-8). The novel excited-state energy distribution-modulated upconversion nanostructure (NaYbF4@NaYF4: Yb, Er) is selected as the fluorescence source and energy donor for highly efficient fluorescence resonance energy transfer (FRET). CuxOS NP is employed as chiral source and energy acceptor to quench upconversion luminescence (UCL) and provide circular dichroism (CD) signal. Utilizing the natural adsorption and sorting advantages of ZIF-8, the designed nanoprobe can isolate the influence of other common disruptors, thus achieve ultra-sensitive and highly selective UCL/CD dual-mode quantification of H2S in aqueous solution and in living cells. Notably, the nanoprobe is also capable of in vivo intra-tumoral H2S tracking. Our work highlights the multifunctional properties of chiral nanocomposites in sensing and opens a new vision and idea for the preparation and application of chiral nanomaterials in biomedical and biological analysis.  
        
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    • Ziyang Li,Yequan Chen,Anke Song,Jinzhong Zhang,Rong Zhang,Zongzhi Zhang,Xuefeng Wang
      Vol. 13, Issue 9, Pages: 1888-1897(2024) DOI: 10.1038/s41377-024-01540-z
      Abstract:Coherent phonons have aroused considerable attention in condensed matter physics owing to their extraordinary capacity of reflecting and controlling the physical properties of matter. However, the investigation on the interaction between coherent phonons and other microscopic particles on the ultrafast timescale within topological systems continues to be an active and unresolved area. Here, we show the energy transfer of coherent optical phonons (COP) in Dirac semimetal PtTe2 thin films using ultrafast optical pump-probe spectroscopy. Specifically, the helicity-dependent light-driven anisotropic COP signals disclose their direct connection with the light-excited anisotropic spin-polarized electrons via an angular momentum transfer. Furthermore, we observe the notable decreases in the COP oscillation frequency and the decay rate with increasing temperatures due to the anharmonic phonon-phonon scattering and electron-phonon scattering in the COP dissipation process, respectively. Our work paves the way for uncovering the coherent phonons in Dirac semimetals for the potential applications in optoelectronics and opto-spintronics.  
        
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    • Bowen Liu,Jialuo Cheng,Maoxiong Zhao,Jin Yao,Xiaoyuan Liu,Shaohu Chen,Lei Shi,Din Ping Tsai,Zihan Geng,Mu Ku Chen
      Vol. 13, Issue 9, Pages: 1898-1907(2024) DOI: 10.1038/s41377-024-01530-1
      Abstract:Metalens, characterized by their unique functions and distinctive physical properties, have gained significant attention for their potential applications. To further optimize the performance of metalens, it is necessary to characterize the phase modulation of the metalens. In this study, we present a multi-distance phase retrieval system based on optical field scanning and discuss its convergence and robustness. Our findings indicate that the system is capable of retrieving the phase distribution of the metalens as long as the measurement noise is low and the total length of the scanned light field is sufficiently long. This system enables the analysis of focal length and aberration by utilizing the computed phase distribution. We extend our investigation to measure the phase distribution of the metalens operating in the near-infrared (NIR) spectrum and identify the impact of defects in the sample on the phase. Additionally, we conduct a comparative analysis of the phase distribution of the metalens in air and ethanol and observe the variations in the phase modulation of the metalens in different working mediums. Our system provides a straightforward method for the phase characterization of metalens, aiding in optimizing the metalens design and functionality.  
        
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    • Gi-Hyun Go,Dong-gu Lee,Jaeyeon Oh,Gookho Song,Doeon Lee,Mooseok Jang
      Vol. 13, Issue 9, Pages: 1908-1918(2024) DOI: 10.1038/s41377-024-01528-9
      Abstract:Shack–Hartmann wavefront sensors measure the local slopes of an incoming wavefront based on the displacement of focal spots created by a lenslet array, serving as key components for adaptive optics for astronomical and biomedical imaging. Traditionally, the challenges in increasing the density and the curvature of the lenslet have limited the use of such wavefront sensors in characterizing slowly varying wavefront structures. Here, we develop a metasurface-enhanced Shack–Hartmann wavefront sensor (meta SHWFS) to break this limit, considering the interplay between the lenslet parameters and the performance of SHWFS. We experimentally validate the meta SHWFS with a sampling density of 5963 per mm2 and a maximum acceptance angle of 8° which outperforms the traditional SFWFS by an order of magnitude. Furthermore, to the best of our knowledge, we demonstrate the first use of a wavefront sensing scheme in single-shot phase imaging of highly complex patterns, including biological tissue patterns. The proposed approach opens up new opportunities in incorporating exceptional light manipulation capabilities of the metasurface platform in complex wavefront characterization.  
        
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    • Yuqiang Ding,Yuchen Gu,Qian Yang,Zhiyong Yang,Yuge Huang,Yishi Weng,Yuning Zhang,Shin-Tson Wu
      Vol. 13, Issue 9, Pages: 1919-1930(2024) DOI: 10.1038/s41377-024-01537-8
      Abstract:Augmented reality (AR) displays, heralded as the next-generation platform for spatial computing, metaverse, and digital twins, empower users to perceive digital images overlaid with real-world environment, fostering a deeper level of human-digital interactions. With the rapid evolution of couplers, waveguide-based AR displays have streamlined the entire system, boasting a slim form factor and high optical performance. However, challenges persist in the waveguide combiner, including low optical efficiency and poor image uniformity, significantly hindering the long-term usage and user experience. In this paper, we first analyze the root causes of the low optical efficiency and poor uniformity in waveguide-based AR displays. We then discover and elucidate an anomalous polarization conversion phenomenon inherent to polarization volume gratings (PVGs) when the incident light direction does not satisfy the Bragg condition. This new property is effectively leveraged to circumvent the tradeoff between in-coupling efficiency and eyebox uniformity. Through feasibility demonstration experiments, we measure the light leakage in multiple PVGs with varying thicknesses using a laser source and a liquid-crystal-on-silicon light engine. The experiment corroborates the polarization conversion phenomenon, and the results align with simulation well. To explore the potential of such a polarization conversion phenomenon further, we design and simulate a waveguide display with a 50° field of view. Through achieving first-order polarization conversion in a PVG, the in-coupling efficiency and uniformity are improved by 2 times and 2.3 times, respectively, compared to conventional couplers. This groundbreaking discovery holds immense potential for revolutionizing next-generation waveguide-based AR displays, promising a higher efficiency and superior image uniformity.  
        
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      Published:2024-09-14
    • Zekun Niu,Hang Yang,Lyu Li,Minghui Shi,Guozhi Xu,Weisheng Hu,Lilin Yi
      Vol. 13, Issue 9, Pages: 1931-1943(2024) DOI: 10.1038/s41377-024-01556-5
      Abstract:The surge in interest regarding the next generation of optical fiber transmission has stimulated the development of digital signal processing (DSP) schemes that are highly cost-effective with both high performance and low complexity. As benchmarks for nonlinear compensation methods, however, traditional DSP designed with block-by-block modules for linear compensations, could exhibit residual linear effects after compensation, limiting the nonlinear compensation performance. Here we propose a high-efficient design thought for DSP based on the learnable perspectivity, called learnable DSP (LDSP). LDSP reuses the traditional DSP modules, regarding the whole DSP as a deep learning framework and optimizing the DSP parameters adaptively based on backpropagation algorithm from a global scale. This method not only establishes new standards in linear DSP performance but also serves as a critical benchmark for nonlinear DSP designs. In comparison to traditional DSP with hyperparameter optimization, a notable enhancement of approximately 1.21 dB in the Q factor for 400 Gb/s signal after 1600 km fiber transmission is experimentally demonstrated by combining LDSP and perturbation-based nonlinear compensation algorithm. Benefiting from the learnable model, LDSP can learn the best configuration adaptively with low complexity, reducing dependence on initial parameters. The proposed approach implements a symbol-rate DSP with a small bit error rate (BER) cost in exchange for a 48% complexity reduction compared to the conventional 2 samples/symbol processing. We believe that LDSP represents a new and highly efficient paradigm for DSP design, which is poised to attract considerable attention across various domains of optical communications.  
        
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      Published:2024-09-14
    • Qian Wang,Chenger Wang,Hongliang Shi,Jie Chen,Junye Yang,Alena Beitlerova,Romana Kucerkova,Zhengyang Zhou,Yunyun Li,Martin Nikl,Xilei Sun,Xiaoping OuYang,Yuntao Wu
      Vol. 13, Issue 9, Pages: 1944-1955(2024) DOI: 10.1038/s41377-024-01532-z
      Abstract:Materials for radiation detection are critically important and urgently demanded in diverse fields, starting from fundamental scientific research to medical diagnostics, homeland security, and environmental monitoring. Low-dimensional halides (LDHs) exhibiting efficient self-trapped exciton (STE) emission with high photoluminescence quantum yield (PLQY) have recently shown a great potential as scintillators. However, an overlooked issue of exciton-exciton interaction in LDHs under ionizing radiation hinders the broadening of its radiation detection applications. Here, we demonstrate an exceptional enhancement of exciton-harvesting efficiency in zero-dimensional (0D) Cs3Cu2I5:Tl halide single crystals by forming strongly localized Tl-bound excitons. Because of the suppression of non-radiative exciton-exciton interaction, an excellent α/β pulse-shape-discrimination (PSD) figure-of-merit (FoM) factor of 2.64, a superior rejection ratio of 10−9, and a high scintillation yield of 26 000 photons MeV−1 under 5.49 MeV α-ray are achieved in Cs3Cu2I5:Tl single crystals, outperforming the commercial ZnS:Ag/PVT composites for charged particle detection applications. Furthermore, a radiation detector prototype based on Cs3Cu2I5:Tl single crystal demonstrates the capability of identifying radioactive 220Rn gas for environmental radiation monitoring applications. We believe that the exciton-harvesting strategy proposed here can greatly boost the applications of LDHs materials.  
        
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      Published:2024-09-14
    • Jianbo De,Ruiyang Zhao,Fan Yin,Chunling Gu,Teng Long,Han Huang,Xue Cao,Cunbin An,Bo Liao,Hongbing Fu,Qing Liao
      Vol. 13, Issue 9, Pages: 1956-1963(2024) DOI: 10.1038/s41377-024-01531-0
      Abstract:Achieving high-luminescence organic light-emitting devices (OLEDs) with narrowband emission and high color purity is important in various optoelectronic fields. Laser displays exhibit outstanding advantages in next-generation display technologies owing to their ultimate visual experience, but this remains a great challenge. Here, we develop a novel OLED based organic single crystals. By strongly coupling the organic exciton state to an optical microcavity, we obtain polariton electroluminescent (EL) emission from the polariton OLEDs (OPLEDs) with high luminance, narrow-band emission, high color purity, high polarization as well as excellent optically pumped polariton laser. Further, we evaluate the potential for electrically pumped polariton laser through theoretical analysis and provide possible solutions. This work provides a powerful strategy with a material–device combination that paves the way for electrically driven organic single-crystal-based polariton luminescent devices and possibly lasers.  
        
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      Published:2024-09-14
    • Xuejuan Wu,Ning Zhou,Yang Chen,Jiasong Sun,Linpeng Lu,Qian Chen,Chao Zuo
      Vol. 13, Issue 9, Pages: 1964-1979(2024) DOI: 10.1038/s41377-024-01568-1
      Abstract:Lens-free on-chip microscopy is a powerful and promising high-throughput computational microscopy technique due to its unique advantage of creating high-resolution images across the full field-of-view (FOV) of the imaging sensor. Nevertheless, most current lens-free microscopy methods have been designed for imaging only two-dimensional thin samples. Lens-free on-chip tomography (LFOCT) with a uniform resolution across the entire FOV and at a subpixel level remains a critical challenge. In this paper, we demonstrated a new LFOCT technique and associated imaging platform based on wavelength scanning Fourier ptychographic diffraction tomography (wsFPDT). Instead of using angularly-variable illuminations, in wsFPDT, the sample is illuminated by on-axis wavelength-variable illuminations, ranging from 430 to 1200 nm. The corresponding under-sampled diffraction patterns are recorded, and then an iterative ptychographic reconstruction procedure is applied to fill the spectrum of the three-dimensional (3D) scattering potential to recover the sample's 3D refractive index (RI) distribution. The wavelength-scanning scheme not only eliminates the need for mechanical motion during image acquisition and precise registration of the raw images but secures a quasi-uniform, pixel-super-resolved imaging resolution across the entire imaging FOV. With wsFPDT, we demonstrate the high-throughput, billion-voxel 3D tomographic imaging results with a half-pitch lateral resolution of 775 nm and an axial resolution of 5.43 μm across a large FOV of 29.85 mm2 and an imaging depth of > 200 μm. The effectiveness of the proposed method was demonstrated by imaging various types of samples, including micro-polystyrene beads, diatoms, and mouse mononuclear macrophage cells. The unique capability to reveal quantitative morphological properties, such as area, volume, and sphericity index of single cell over large cell populations makes wsFPDT a powerful quantitative and label-free tool for high-throughput biological applications.  
        
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      Published:2024-09-14
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