Dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates

Interactive holography offers unmatched levels of immersion and user engagement in the field of future display.Despite of the substantial progress has been made in dynamic meta-holography,the realization of real-time,highly smooth interactive holography remains a significant challenge due to the computational and display frame rate limitations.In this study,we introduced a dynamic interactive bitwise meta-holography with ultra-high computational and display frame rates.To our knowledge,this is the first reported practical dynamic interactive metasurface holographic system.We spa-tially divided the metasurface device into multiple distinct channels,each projecting a reconstructed sub-pattern.The switching states of these channels were mapped to bitwise operations on a set of bit values,which avoids complex holo-gram computations,enabling an ultra-high computational frame rate.Our approach achieves a computational frame rate of 800 kHz and a display frame rate of 23 kHz on a low-power Raspberry Pi computational platform.According to this methodology,we demonstrated an interactive dynamic holographic Tetris game system that allows interactive gameplay,color display,and on-the-fly hologram creation.Our technology presents an inspiration for advanced dynamic meta-holography,which is promising for a broad range of applications including advanced human-computer interaction,real-time 3D visualization,and next-generation virtual and augmented reality systems.

Efficient stochastic parallel gradient descent training for on-chip optical processor

In recent years,space-division multiplexing(SDM)technology,which involves transmitting data information on multiple parallel channels for efficient capacity scaling,has been widely used in fiber and free-space optical communication sys-tems.To enable flexible data management and cope with the mixing between different channels,the integrated reconfig-urable optical processor is used for optical switching and mitigating the channel crosstalk.However,efficient online train-ing becomes intricate and challenging,particularly when dealing with a significant number of channels.Here we use the stochastic parallel gradient descent(SPGD)algorithm to configure the integrated optical processor,which has less com-putation than the traditional gradient descent(GD)algorithm.We design and fabricate a 6×6 on-chip optical processor on silicon platform to implement optical switching and descrambling assisted by the online training with the SPDG algorithm.Moreover,we apply the on-chip processor configured by the SPGD algorithm to optical communications for optical switching and efficiently mitigating the channel crosstalk in SDM systems.In comparison with the traditional GD al-gorithm,it is found that the SPGD algorithm features better performance especially when the scale of matrix is large,which means it has the potential to optimize large-scale optical matrix computation acceleration chips.

Pixelated non-volatile programmable photonic integrated circuits with 20-level intermediate states

Multi-level programmable photonic integrated circuits(PICs)and optical metasurfaces have gained widespread attention in many fields,such as neuromorphic photonics,opticalcommunications,and quantum information.In this paper,we propose pixelated programmable Si_(3)N_(4)PICs with record-high 20-level intermediate states at 785 nm wavelength.Such flexibility in phase or amplitude modulation is achieved by a programmable Sb_(2)S_(3)matrix,the footprint of whose elements can be as small as 1.2μm,limited only by the optical diffraction limit of anin-house developed pulsed laser writing system.We believe our work lays the foundation for laser-writing ultra-high-level(20 levels and even more)programmable photonic systems and metasurfaces based on phase change materials,which could catalyze diverse applications such as programmable neuromorphic photonics,biosensing,optical computing,photonic quantum computing,and reconfigurable metasurfaces.

Secure optical interconnects using orbital angular momentum beams multiplexing/multicasting

Orbital angular momentum(OAM),described by an azimuthal phase term expej lθT,has unbound orthogonal states with different topological charges l.Therefore,with the explosive growth of global communication capacity,especially for short-distance optical interconnects,light-carrying OAM has proved its great potential to improve transmission capacity and spectral efficiency in the space-division multiplexing system due to its orthogonality,security,and compatibility with other techniques.Meanwhile,100-m freespace optical interconnects become an alternative solution for the“last mile”problem and provide interbuilding communication.We experimentally demonstrate a 260-m secure optical interconnect using OAM multiplexing and 16-ary quadrature amplitude modulation(16-QAM)signals.We study the beam wandering,power fluctuation,channel cross talk,bit-error-rate performance,and link security.Additionally,we also investigate the link performance for 1-to-9 multicasting at the range of 260 m.Considering that the power distribution may be affected by atmospheric turbulence,we introduce an offline feedback process to make it flexibly controllable.

Recent advances in two-dimensional photovoltaic devices

Two-dimensional(2D)materials have attracted tremendous interest in view of the outstanding optoelectronic properties,showing new possibilities for future photovoltaic devices toward high performance,high specific power and flexibility.In recent years,substantial works have focused on 2D photovoltaic devices,and great progress has been achieved.Here,we present the review of recent advances in 2D photovoltaic devices,focusing on 2D-material-based Schottky junctions,homojunctions,2D−2D heterojunctions,2D−3D heterojunctions,and bulk photovoltaic effect devices.Furthermore,advanced strategies for improving the photovoltaic performances are demonstrated in detail.Finally,conclusions and outlooks are delivered,providing a guideline for the further development of 2D photovoltaic devices.

Generation of subwavelength inverted pin beam via fiber end integrated plasma structure

A pin-like beam is a kind of structured light with a special intensity distribution that can be against diffraction,which can be seen as a kind of quasi-nondiffracting beam(Q-NDB).Due to its wide applications,recently,numerous researchers have used optical lenses or on-chip integrated optical diffractive elements to generate this kind of beam.We theoretically verify and experimentally demonstrate an all-fiber solution to generate a subwavelength inverted pin beam by integrating a simple plasma structure on the fiber end surface.The output beams generated by two kinds of plasma structures,i.e.,nanoring slot and nanopetal structure,are investigated and measured experimentally.The results show that both the structures are capable of generating subwavelength beams,and the beam generated using the nanopetal structure has the sidelobe suppression ability along the x-axis direction.Our all-fiber device can be flexibly inserted into liquid environments such as cell cultures,blood,and biological tissue fluids to illuminate or stimulate biological cells and molecules in them.It provides a promising fiber-integrated solution for exploring light–matter interaction with subwavelength resolution in the field of biological research.

Accelerating the evaluation of operational lifetimes of perovskite solar cells and modules

Compared with the power conversion efficicency,the operational stability of perovskite solar cells(PsCs)remains a major challenge hampering its commercialization.However,conducting a light soaking test under 1 sun illumination to get a long lifetime is time-consuming and experimentally inefficient.Here,we report an accelerated stability test protocol by aging PsCs under high-intensity light illumination to accelerate the evaluation of their operation stability.It is found that the efficiency degradation rate of a typical inverted PsC is almost linearly dependent on the light intensity within the range of 1 to 4 suns regardless of the encapsulations.The results prove that it can save the light-soaking time by at least 4 times to predict the operation lifetime on the basis of the equivalent light irradiation dose.

Relative timing jitter compression in a Fabry-Pérot cavity-assisted free-running dual-comb interferometry

Dual-comb interferometric systems with high time accuracy have been realized for various applications.The flourishing ultralow noise dual-comb system promotes the measurement and characterization of relative timing jitter,thus improving time accuracy.With optical solutions,introducing an optical reference enables 105 harmonics measurements,thereby breaking the limit set by electrical methods;nonlinear processes or spectral interference schemes were also employed to track the relative timing jitter.However,such approaches operating in the time domain either require additional continuous references or impose stringent requirements on the amount of timing jitter.We propose a scheme to correct the relative timing jitter of a free-running dual-comb interferometry assisted by a Fabry-Pérot(F-P)cavity in the frequency domain.With high wavelength thermal stability provided by the F-P cavity,the absolute wavelength deviation in the operating bandwidth is compressed to<0.4 pm,corresponding to a subpicosecond sensitivity of pulse-to-pulse relative timing jitter.Also,Allan deviation of 10^(-10) is obtained under multiple coherent averaging,which lays the foundation for mode-resolved molecular spectroscopic applications.The spectral absorption features of hydrogen cyanide gas molecules at ambient temperature were measured and matched to the HITRAN database.Our scheme promises to provide new ideas on sensitive measurements of relative timing jitter.

Redefinable neural network for structured light array

Neural networks have provided faster and more straightforward solutions for laser modulation.However,their effectiveness when facing diverse structured lights and various output resolutions remains vulnerable because of the specialized end-to-end training and static model.Here,we propose a redefinable neural network(RediNet),realizing customized modulation on diverse structured light arrays through a single general approach.The network input format features a redefinable dimension designation,which ensures RediNet wide applicability and removes the burden of processing pixel-wise light distributions.The prowess of originally generating arbitrary-resolution holograms with a fixed network is first demonstrated.The versatility is showcased in the generation of 2D/3D foci arrays,Bessel and Airy beam arrays,(perfect)vortex beam arrays,and even snowflake-intensity arrays with arbitrarily built phase functions.A standout application is producing multichannel compound vortex beams,where RediNet empowers a spatial light modulator(SLM)to offer comprehensive multiplexing functionalities for free-space optical communication.Moreover,RediNet has the hitherto highest efficiency,only consuming 12 ms(faster than the mainstream SLM framerate of 60 Hz)for a 1000^(2)-resolution holograph,which is critical in real-time required scenarios.Considering the fine resolution,high speed,and unprecedented universality,RediNet can serve extensive applications,such as next-generation optical communication,parallel laser direct writing,and optical traps.

Robust spectral reconstruction algorithm enables quantum dot spectrometers with subnanometer spectral accuracy

Since the concept of computational spectroscopy was introduced,numerous computational spectrometers have emerged.While most of the work focuses on materials,optical structures,and devices,little attention is paid to the reconstruction algorithm,thus resulting in a common issue:the effectiveness of spectral reconstruction is limited under high-level noise originating from the data acquisition process.Here,we fabricate a computational spectrometer based on a quantum dot(QD)filter array and propose what we believe is a novel algorithm,TKVA(algorithm with Tikhonov and total variation regularization,and the alternating direction method of multipliers),to suppress the impact of noise on spectral recovery.Surprisingly,the new TKVA algorithm gives rise to another advantage,i.e.,the spectral accuracy can be enhanced through interpolation of the precalibration data,providing a convenient solution for performance improvement.In addition,the accuracy of spectral recovery is also enhanced via the interpolation,highlighting its superiority in spectral reconstruction.As a result,the QD spectrometer using the TKVA algorithm shows supreme spectral recovery accuracy compared to the traditional algorithms for complex and broad spectra,a spectral accuracy as low as 0.1 nm,and a spectral resolution of 2 nm in the range of 400 to 800 nm.The new reconstruction algorithm can be applied in various computational spectrometers,facilitating the development of this kind of equipment.

苏鲁两省意大利杨和中华红叶杨白粉病的病原菌研究

2011～2012年通过对苏鲁两省杨树白粉病害的调查,采集病原标本进行了室内切片鉴定,描述了症状及病原菌的形态,分析了寄主及分布范围。结果表明,根据病原菌的形态特征,引起苏鲁两省杨树白粉病的病原菌被鉴定为杨球针壳,该菌为害I-69杨、I-72杨、I-107杨、NL895杨和中华红叶杨属首次报道。杨球针壳能寄生在多种杨树上,严重时引起杨树提前落叶;同时发现,杨球针壳、落叶松杨叶锈菌的夏孢子阶段和杨盘二孢菌3种病原菌同时生长在同一张杨树叶片上,引起3种类型的病害症状,这种现象也属首次报道。

热带头梗霉在中国NL351杨树上的首次发现

为研究NL351杨树上的真菌种类,对其杨木边材进行了组织分离,通过纯化培养,得到了内生菌热带头梗霉(Cephaliophora tropica)。采用形态特征和分子生物技术相结合的方法对其热带头梗霉进行了确凿鉴定,并确认分布于中国的NL351杨树是热带头梗霉的新寄主,此菌在杨树上发现属于首次报道。

壳针孢(Septoria musiva)引起的杨树病害

壳针孢引起多种杨树病害,已危及到森林健康,造成了严重的经济损失。该文概述了Septoriamusiva引起的杨树病害症状类型、侵染规律、寄主抗性和防治措施。

MyShake一个跨界的系统:智能手机用于地震预警

在城市地区发生的大地震可以造成重大人员伤亡,引发社会和经济灾难。地震预警(Earthquake Early Warning,EEW)可以提供秒到分钟的警报,让人们转移到安全区,使工厂停工,车辆减速和刹车。目前世界上只在少数国家使用传统的地震台网和大地测量观测网运行EEW系统。智能手机比传统地震台网更为广泛和普及,它内置了可检测地震的加速度计。我们开发了一种新的测震系统称为MyShake,它利用智能手机内置传感器来收集数据并分析地震。智能手机MyShake系统可以从日常的各种震动中检测到距手机10km或以内的5级地震。这些数据汇集到观测中心,经过一定的算法处理,可以实时测定地震的位置和震级,发出地震预警信息,证明我们的理念是可行的。对没有地震预警系统的区域,MyShake系统可提供地震预警,而对有预警系统的区域,MyShake系统是对原系统预警能力的补充和增强。此外,该系统地震波形记录可以用来提供快速地震烈度图,以评估地震对建筑物的影响,还可以获取地球内部浅层结构图像和地震破裂过程。

Acousto-optic scanning spatial-switching multiphoton lithography

Nano-3D printing has obtained widespread attention owing to its capacity to manufacture end-use components with nano-scale features in recent years.Multiphoton lithography(MPL)is one of the most promising 3D nanomanufacturing technologies,which has been widely used in manufacturing micro-optics,photonic crystals,microfluidics,meta-surface,and mechanical metamaterials.Despite of tremendous potential of MPL in laboratorial and industrial applications,simultaneous achievement of high throughput,high accuracy,high design freedom,and a broad range of material structuring capabilities remains a long-pending challenge.To address the issue,we propose an acousto-optic scanning with spatial-switching multispots(AOSS)method.Inertia-free acousto-optic scanning and nonlinear swept techniques have been developed for achieving ultrahigh-speed and aberration-free scanning.Moreover,a spatial optical switch concept has been implemented to significantly boost the lithography throughput while maintaining high resolution and high design freedom.An eight-foci AOSS system has demonstrated a record-high 3D printing rate of 7.6×10^(7)voxel s^(-1),which is nearly one order of magnitude higher than earlier scanning MPL,exhibiting its promise for future scalable 3D nanomanufacturing.

Multi-foci metalens for spectra and polarization ellipticity recognition and reconstruction

Multispectral and polarized focusing and imaging are key functions that are vitally important for a broad range of optical applications.Conventional techniques generally require multiple shots to unveil desired optical information and are implemented via bulky multi-pass systems or mechanically moving parts that are difficult to integrate into compact and integrated optical systems.Here,a design of ultra-compact transversely dispersive metalens capable of both spectrum and polarization ellipticity recognition and reconstruction in just a single shot is demonstrated with both coherent and incoherent light.Our design is well suited for integrated and high-speed optical information analysis and can significantly reduce the size and weight of conventional devices while simplifying the process of collecting optical information,thereby promising for various applications,including machine vision,minimized spectrometers,material characterization,remote sensing,and other areas which require comprehensive optical analysis.

Integrated photonic convolution acceleration core for wearable devices

With the advancement of deep learning and neural networks,the computational demands for applications in wearable devices have grown exponentially.However,wearable devices also have strict requirements for long battery life,low power consumption,and compact size.In this work,we propose a scalable optoelectronic computing system based on an integrated optical convolution acceleration core.This system enables high-precision computation at the speed of light,achieving 7-bit accuracy while maintaining extremely low power consumption.It also demonstrates peak throughput of 3.2 TOPS(tera operations per second)in parallel processing.We have successfully demonstrated image convolution and the typical application of an interactive first-person perspective gesture recognition application based on depth information.The system achieves a comparable recognition accuracy to traditional electronic computation in all blind tests.

Attosecond spectroscopy for filming the ultrafast movies of atoms,molecules and solids

Three decades ago,a highly nonlinear nonpertubative phenomenon,now well-known as the high harmonic generation(HHG),was discovered when intense laser irradiates gaseous atoms.As the HHG produces broadband coherent radiation,it becomes the most promising source to obtain attosecond pulses.The door to the attosecond science was opened ever since.In this review,we will revisit the incredible adventure to the attoworld.Firstly,the progress of attosecond pulse generation is outlined.Then,we introduce the efforts on imaging the structures or filming the ultrafast dynamics of nuclei and electrons with unprecedented attosecond temporal and Angstrom spatial resolutions,utilizing the obtained attosecond pulses as well as the high harmonic spectrum itself.

Wavelength-and ellipticity-dependent photoelectron spectra from multiphoton ionization of atoms

We theoretically study the photoelectron momentum distributions from multiphoton ionization of a model lithium atom over a range of laser wavelengths from 500 nm to 700 nm by numerically solving the time-dependent Schr ¨odinger equation. The photoelectron momentum distributions display many ring-like patterns for the three-photon ionization, which vary dramatically with the change of the laser wavelength. We show that the wavelength-dependent photoelectron energy spectrum can be used to effectively identify the resonant and nonresonant ionization pathways. We also find an abnormal ellipticity dependence of the electron yield for the(2+1) resonance-enhanced ionization via the 4d intermediate state, which is relevant to the two-photon excitation probability from the ground state to the 4d state.

钙钛矿太阳能电池的发展现状和未来趋势

1.Introduction Carbon neutrality is an important strategy to address the acute problems of resource and environmental constraints.Currently,afforestation,energy conservation,emissions reduction,and other measures have been adopted to offset the total amount of carbon dioxide and other greenhouse gas emissions generated by countries,businesses,products,activities,or individuals,with the aim of finally achieving zero net emissions(Fig.1(a)).