bluuebunny/crossref_metadata_2025 huggingface dataset:
A new mechanism of fibronectin fibril assembly revealed by live imaging and super-resolution microscopy
Authors: Tomer Darshika , Arriagada Cecilia , Munshi Sudipto , Alexander Brianna E. , French Brenda , Vedula Pavan , Caorsi Valentina , House Andrew , Guvendiren Murat , Kashina Anna , Schwarzbauer Jean E. , Astrof Sophie
Published: July 2022

Fibronectin (Fn1) fibrils have long been viewed as continuous fibers composed of extended, periodically aligned Fn1 molecules. However, our live-imaging and single-molecule localization microscopy data are inconsistent with this traditional view and show that Fn1 fibrils are composed of roughly spherical nanodomains containing six to eleven Fn1 dimers. As they move toward the cell center, Fn1 nanodomains become organized into linear arrays, in which nanodomains are spaced with an average periodicity of 105±17 nm. Periodical Fn1 nanodomain arrays can be visualized between cells in culture and within tissues; they are resistant to deoxycholate treatment and retain nanodomain periodicity in the absence of cells. The nanodomain periodicity in fibrils remained constant when probed with antibodies recognizing distinct Fn1 epitopes or combinations of antibodies recognizing epitopes spanning the length of Fn1. Treatment with FUD, a peptide that binds the Fn1 N-terminus and disrupts Fn1 fibrillogenesis, blocked the organization of Fn1 nanodomains into periodical arrays. These studies establish a new paradigm of Fn1 fibrillogenesis.

This article has an associated First Person interview with the first author of the paper.
Divergence of climbing escape flight performance inMorphobutterflies living in different microhabitats
Authors: Le Roy Camille , Silva Nicolas , Godoy-Diana Ramiro , Debat Vincent , Llaurens Violaine , Muijres Florian Titus
Published: July 2022

Habitat specialization can influence the evolution of animal movement in promoting divergent locomotor abilities adapted to contrasting environmental conditions, differences in vegetation clutter or predatory communities. While the effect of habitat on the evolution of locomotion and particularly escape performance has been well investigated in terrestrial animals, it remains understudied in flying animals. Here, we investigated whether specialization of Morpho butterfly species into different vertical strata of the Amazonian forest affects the performance of upward escape flight manoeuvres. Using stereoscopic high-speed videography, we compared the climbing flight kinematics of seven Morpho species living either in the forest canopy or in the understory. We show that butterflies from canopy species display strikingly higher climbing speed and steeper ascent angle compared with understory species. Although climbing speed increased with wing speed and angle of attack, the higher climb angle observed in canopy species was best explained by their higher body pitch angle, resulting in more upward-directed aerodynamic thrust forces. Climb angle also scales positively with weight-normalized wing area, and this weight-normalized wing area was higher in canopy species. This shows that a combined divergence in flight behaviour and morphology contributes to the evolution of increased climbing flight abilities in canopy species.
Edge-Weighted Online Windowed Matching
Authors: Ashlagi Itai , Burq Maximilien , Dutta Chinmoy , Jaillet Patrick , Saberi Amin , Sholley Chris
Published: July 2022

Consider a matching problem, in which agents arrive to a marketplace over time and leave after some time periods. Agents can only be matched while present in the marketplace. Each pair of agents can yield a different match value, and a social planner seeks to maximize the total value from matches over a finite time horizon. First we study the case in which vertices arrive in an adversarial order. For the case when agents depart in the order of arrival, we provide a randomized [Formula: see text]-competitive algorithm. When departure times are drawn independently from a distribution with nondecreasing hazard rate, we establish a [Formula: see text]-competitive algorithm. When the arrival order is chosen uniformly at random and agents leave after a fixed number of time periods, a batching algorithm, which computes a maximum-weighted matching periodically, is shown to be 0.279-competitive.
The Anchor-Robust Project Scheduling Problem
Authors: Bendotti Pascale , Chrétienne Philippe , Fouilhoux Pierre , Pass-Lanneau Adèle
Published: July 2022

In project scheduling, the durations of activities are often uncertain. Delays may cause a massive disorganization if a large number of activities must be rescheduled. In “The Anchor-Robust Project Scheduling Problem,” Bendotti, Chrétienne, Fouilhoux, and Pass-Lanneau propose a novel criterion for solution stability in project scheduling under processing times uncertainty. They define anchored jobs as jobs whose starting times can be guaranteed in a baseline schedule. Finding a project schedule with bounded makespan and a max-weight set of anchors is shown to be an NP-hard robust two-stage problem. Taking advantage of the combinatorial structure of project scheduling and budgeted uncertainty, the authors obtain a compact MIP formulation for the problem. Numerical results show that the obtained MIP outperforms standard techniques from the literature. They also showcase the practical interest of anchored jobs in project scheduling.
Desastres ambientais e a percepção de riscos na cidade
Authors: Firmo Clóvis Peixoto , Rocha Érica Tavares da Silva
Published: July 2022

ResumoO processo de urbanização e sua relação com a dinâmica ambiental revela a desigual distribuição dos ganhos e custos ambientais e sociais nas cidades, sobretudo quando abordamos as situações de desastre, levando à compreensão de que os desastres são processos socialmente construídos. O objetivo deste artigo é analisar as condições sociais e de infraestrutura urbana, assim como a percepção sobre o risco, em uma área urbana com ocorrência de desastres ambientais, articulando referenciais teóricos sobre ocupação do espaço urbano, riscos e desastres. A metodologia utilizada baseou-se em pesquisa quantitativa com a realização de um survey domiciliar por meio de entrevistas estruturadas na localidade de Ururaí em Campos dos Goytacazes, Rio de Janeiro, Brasil. Ao analisarmos a relação entre o espaço físico e social nas cidades brasileiras, observa-se que a diferenciação social, que se manifesta nos processos de ocupação e apropriação do espaço, também está relacionada à suscetibilidade da população aos desastres ambientais nas periferias das cidades. Muitos indivíduos e famílias são constrangidos, por vários fatores sociais e econômicos, a construírem suas moradias em áreas sujeitas a alagamentos, inundações e deslizamentos.Palavras-Chave: desastres ambientais, risco, cidade, desigualdades.
A atualidade de Vitaliano Brancati: figurações do masculino e do feminino em Il bell’Antonio e a construção de gêneros na sociedade brasileira
Authors: Rodrigues Rodrigo Vicente
Published: July 2022

RESUMO: Partindo da obra Il bell’Antonio, de Vitaliano Brancati, este artigo visa a verificar como são construídas as noções de feminino e masculino dentro do romance e a demonstrar como a nossa sociedade contemporânea ecoa muitos pontos do mundo siciliano do primo novecento evocados pelo escritor. Para tanto foram usados textos teóricos que focam a questão da construção dos gêneros como algo social e historicamente condicionado, o que se mostra particularmente importante neste momento, em que se vê um recrudescimento de discursos conservadores e uma guinada à direita no Brasil. Nesse sentido, demonstrar-se-á a atualidade da obra de Brancati e a importância da literatura como convite à alteridade e à reflexão para se pensar a própria realidade, mesmo apesar da distância temporal e da diferença de contextos entre a realidade que Il bell’Antonio encerra e a nossa.Palavras-chave: Masculinidade. Feminilidade. Literatura italiana. Machismo.ABSTRACT: Basato sul libro Il bell'Antonio, di Vitaliano Brancati, questo articolo si propone di verificare come le nozioni di femminile e maschile siano costruite all'interno del romanzo e di dimostrare come la nostra società contemporanea rifletta molti punti del mondo siciliano del primo novecento evocati in quest’opera. Pertanto, i testi teorici che si concentrano sulla costruzione di generi sono stati impiegati al fine di dimostrare che essa è qualcosa di condizionato socialmente e storicamente. Ciò è particolarmente importante in questo momento, quando in Brasile c'è un aumento dei discorsi conservatori e una svolta a destra. In questo contesto verrà dimostrata la rilevanza dell'opera di Brancati e l'importanza della letteratura come invito all'alterità e alla riflessione su la realtà attuale, a dispetto della distanza temporale e della differenza di contesti tra la realtà che Il bell 'Antonio mostra e la nostra.Parole-chave: Mascolinità. Feminilità. Letteratura italiana. Maschilismo.ABSTRACT: Based on the work Il bell'Antonio, by Vitaliano Brancati, this article aims to verify how the notions of feminine and masculine are constructed within the novel and to demonstrate how our contemporary society echoes many points of the Sicilian world evoked by the writer in his work. To do so, theoretical texts that focus on the issue of gender construction as something social and historically conditioned were used. This is particularly important at this moment, when the conservative discourses and the far-right increase in Brazil. In this context, the relevance of Brancati's work is evocated as something very current and the importance of literature as an invitation to otherness and reflection to think about the reality itself will be demonstrated, in spite of the temporal distance and the difference of contexts between the reality of Il bell 'Antonio and ours.Keywords: Masculinity. Femininity. Italian literature. Male Chauvinism.
B-Spot: Blockchain and Steganography based Robust and Secure Photo Transmission Mechanism
Authors: Li Dongchi , Kar Pushpendu
Published: July 2022

In this paper, a Steganography and Blockchain based robust and secure photo transmission mechanism, named B-Spot, is proposed. At the sender side, firstly, a 3-3-2 LSB image steganography algorithm is used to hide a secret photo into a cover photo. Therefore, the existence of the secret photo is concealed. Then the stego-image is broken down into pixels and embedded into blocks. Blocks are connected by the hash values forming a blockchain. Any modifications on the blocks are reflected by the breakage of the chain, which makes the mechanism tamper-evident. Another copy of the blockchain is stored in a hash table for the latter recovery process. The blockchain and the hash table can be transmitted via any network. When the receiver receives the data, it firstly executes the verification process to check integrity of the blockchain. Then the lost and tampered blocks are recovered by referring to the hash table, which makes the mechanism more robust to noises. Finally, the stego-image is reconstructed from the recovered blockchain. Then the receiver can obtain the secret photo following the extraction algorithm. The simulation results show that the proposed mechanism has high data capacity, better imperceptibility, reasonable computing time, and strong robustness to noise. This mechanism adds an extra layer of security and robustness to the existing schemes.
An Enhance the Performance of Mining Vehicular and Machinery Security Systems Using Artificial Intelligence in VANET Cloud Computing
Authors: Al-Shabi M.
Published: July 2022

Over the recent decades, incorporating Vehicular Ad-hoc Network (VANET) into Cloud computing plays a vital role, since it provides a reliable safety journey to vehicular drivers, passengers, etc. However, attaining security and emergency message dissemination is still major bottleneck in VANET combined Cloud, due to the dynamic nature of vehicles and wireless communication. Our major intention is to provide high level security in VANET-Cloud environment. In addition to it, we also reduce delay in emergency dissemination. Our proposed Delay aware Emergency Message Dissemination and Data Retrieval in secure (DEMD22RS) VANET-Cloud is composed of four sequential processes: Authentication, Clustering, Data Retrieval and Data dissemination. In regard to maintaining security for both Road Side Unit (RSU) and Vehicles, we propose Hash based Credential Authentication Scheme (HCAS) that affords authentication using Secure Hash Algorithm-3 (SHA-3) and Elliptic Curve Points (ECP). To sustain a stable cluster, Firm Aware Clustering Scheme (FACS) is pursued where Stud Krill Herd (SKH) algorithm is exploited. In the data retrieval process, cloud provides requested information to the RSU in encrypted form using the Twofish algorithm. RSU discover the path to deliver received data through executing Artificial Neural Network (ANN) algorithm. In order to diminish delay in emergency message dissemination, best disseminator is selected by cluster head using Fuzzy-Topsis (FT) algorithm. Our DEMD22RS VANET-Cloud network is implemented in Network Simulator 3 tool. Finally, the evaluation of DEMD22RS work performance is achieved by computing consequent metrics that are Throughput, Packet Delivery Ratio, Transmission delay, Average delay, Key generation time, Encryption time and Decryption time.
An Electronic Double Auction of Prepaid Electricity Trading Using Blockchain Technology
Authors: Wongsamerchue Thammavich , Leelasantitham Adisorn
Published: July 2022

Thailand’s current energy trading system is an Enhanced Single Buyer (ESB), a market monopoly by a single buyer. It will produce and distribute electricity to service providers in each area, enabling them to distribute services to consumers. In terms of the consumer aspect, it is necessary to purchase electricity from only one seller, and it is not possible to choose the manufacturer independently. Since the price mechanism is not competitive, the market price is mainly determined by a single buyer. Meanwhile, alternative energy power generation technology has progressed. Anyone can become a power producer using wind power or solar energy. People can easily produce electricity to use in their households. Besides, residual energy from use will be sold only to the ESB. However, there is a selling restriction because there is only one buyer. Importantly, Blockchain technology can be applied to enable independent electricity trading. In other words, called peer-to-peer (P2P) trading, the Thai government has policies to promote P2P trading. However, there are not many systems supporting P2P energy trading since P2P trading is still in the beginning stages of the Pilot Project. In this study, the researchers have presented a P2P Power Trading Model using Blockchain technology. This research presents a system with efficiency and simplicity. Also, there are other technology highlights such as IoT, Lora, and Electronic Double Auction. The researcher has designed, implemented, and tested it for actual electrical power trading. It can prove to be traded according to the designed test cases. Importantly, we are truly confident that this research will benefit those interested in developing real-world applications. This research can also be used as an alternative to the traditional power purchase and sale system.
A Hybrid Approach Based Diet Recommendation System Using ML and Big Data Analytics
Authors: Lambay Muhib Anwar , Mohideen S. Pakkir
Published: July 2022

Recommendations are useful suggestions used by people from all walks of life. However, the usage of recommender systems plays a vital role in modern applications. They are found in different domains such as E-commerce. Concerning the health care industry, recommendations play a very crucial role. This industry has significance as it is linked to the lives of people and their well-being. Human health depends on the diet followed. Keeping this fact in mind, in this paper, we investigated healthy diet recommendations. The recommender systems that are existing in healthcare focused a little in this area. From the literature, it is understood that most of the frameworks on health recommendations are theoretical in nature. As food decides health, it is to be given paramount importance. In this paper, we proposed a hybrid mechanism based on Artificial Intelligence (AI) for big data analytics. Particularly we used Machine Learning (ML) for generating healthy diet recommendations. The proposed system is known as Hybrid Recommender System (HRS). It involves a hybrid approach with Natural Language Processing (NLP) and machine learning. An algorithm named Intelligent Recommender for Healthy Diet (IR-HD) is proposed to analyze data and provide healthy diet recommendations. IR-HD could generate recommendations on a healthy diet and outperform existing models. Python data science platform is used to implement the recommender system. The results of experiments showed that the system is capable of providing quality recommendations and it has performance improvement over the state of the art.
Offline Automatic Speech Recognition System Based on Bidirectional Gated Recurrent Unit (Bi-GRU) with Convolution Neural Network
Authors: Girirajan S. , Pandian A.
Published: July 2022

In recent years, the usage of smart phones increased rapidly. Such smartphones can be controlled by natural human speech signals with the help of automatic speech recognition (ASR). Since a smartphone is a small gadget, it has various limitations like computational power, battery, and storage. But the performance of the ASR system can be increased only when it is in online mode since it needs to work from the remote server. The ASR system can also work in offline mode, but the performance and accuracy are less when compared with online ASR. To overcome the issues that occur in the offline ASR system, we proposed a model that combines the bidirectional gated recurrent unit (Bi-GRU) with convolution neural network (CNN). This model contains one layer of CNN and two layers of gated Bi-GRU. CNN has the potential to learn local features. Similarly, Bi-GRU has expertise in handling long-term dependency. The capacity of the proposed model is higher when compared with traditional CNN. The proposed model achieved nearly 5.8% higher accuracy when compared with the previous state-of-the-art methods.
Design and characterization of a time-domain optical tomography platform for mesoscopic lifetime imaging
Authors: Gao Shan , Li Mengzhou , Smith Jason T. , Intes Xavier
Published: July 2022

We report on the system design and instrumental characteristics of a novel time-domain mesoscopic fluorescence molecular tomography (TD-MFMT) system for multiplexed molecular imaging in turbid media. The system is equipped with a supercontinuum pulsed laser for broad spectral excitation, based on a high-density descanned raster scanning intensity-based acquisition for 2D and 3D imaging and augmented with a high-dynamical range linear time-resolved single-photon avalanche diode (SPAD) array for lifetime quantification. We report on the system’s spatio-temporal and spectral characteristics and its sensitivity and specificity in controlled experimental settings. Also, a phantom study is undertaken to test the performance of the system to image deeply-seated fluorescence inclusions in tissue-like media. In addition, ex vivo tumor xenograft imaging is performed to validate the system’s applicability to the biological sample. The characterization results manifest the capability to sense small fluorescence concentrations (on the order of nanomolar) while quantifying fluorescence lifetimes and lifetime-based parameters at high resolution. The phantom results demonstrate the system’s potential to perform 3D multiplexed imaging thanks to spectral and lifetime contrast in the mesoscopic range (at millimeters depth). The ex vivo imaging exhibits the prospect of TD-MFMT to resolve intra-tumoral heterogeneity in a depth-dependent manner.
Video-rate full-ring ultrasound and photoacoustic computed tomography with real-time sound speed optimization
Authors: Zhang Yachao , Wang Lidai
Published: July 2022

Full-ring dual-modal ultrasound and photoacoustic imaging provide complementary contrasts, high spatial resolution, full view angle and are more desirable in pre-clinical and clinical applications. However, two long-standing challenges exist in achieving high-quality video-rate dual-modal imaging. One is the increased data processing burden from the dense acquisition. Another one is the object-dependent speed of sound variation, which may cause blurry, splitting artifacts, and low imaging contrast. Here, we develop a video-rate full-ring ultrasound and photoacoustic computed tomography (VF-USPACT) with real-time optimization of the speed of sound. We improve the imaging speed by selective and parallel image reconstruction. We determine the optimal sound speed via co-registered ultrasound imaging. Equipped with a 256-channel ultrasound array, the dual-modal system can optimize the sound speed and reconstruct dual-modal images at 10 Hz in real-time. The optimized sound speed can effectively enhance the imaging quality under various sample sizes, types, or physiological states. In animal and human imaging, the system shows co-registered dual contrasts, high spatial resolution (140 µm), single-pulse photoacoustic imaging (< 50 µs), deep penetration (> 20 mm), full view, and adaptive sound speed correction. We believe VF-USPACT can advance many real-time biomedical imaging applications, such as vascular disease diagnosing, cancer screening, or neuroimaging.
Altering apparent optical properties with an array of semitransparent
mesoscale structures
Authors: Kucuktas Onur A. , Kottke Peter A. , Simeroth David L. , Fedorov Andrei G.
Published: July 2022

The ability to control and optimize interactions between light and matter has much utility in engineering design. A well-researched way to achieve optical property modulation is via the use of optical metamaterials, which feature sub-wavelength scale surface structures. In this work, an alternative approach for modulating optical properties is presented using a composite surface modified with a periodic array of semitransparent hemispherical shell mesoscale structures which are larger than the incident light wavelength. A ray-tracing simulation approach is used to predict the optical behavior for an arrayed surface. At oblique angles of incidence, significant increases and decreases in apparent absorptance are achieved via the use of optically thick and thin shells, respectively. Additionally, a potential application to solar cells is described with optimal spectral behavior achieved via the use of semitransparent external structures.
Nonlinear optical frequency conversion by cascaded difference frequency generation
Authors: Li Zhongyang , Zhang Gege , Liu Pengxiang , Chen Xinghai , Xu Juan , Sun Xiangqian , Bing Pibin , Yuan Sheng , Zhong Kai , Yao Jianquan
Published: July 2022

We propose a nonlinear optical frequency conversion method based on cascaded difference frequency generation. Feasible designs are presented that enable the cascaded optical waves. They are initially generated by cascaded difference frequency generation with two pump waves, then transferred to high-order Stokes waves by optimized cascaded difference frequency generation, and finally congregated at a few spectral lines. We demonstrate wide frequency tuning characteristics and high conversion efficiency characteristics of the nonlinear frequency convertor by providing a theoretical framework. The frequency tuning from 291 THz to 175 THz and energy conversion efficiency exceeding 30% are achieved by numerical calculations. The nonlinear frequency convertor exhibits physics distinctly different from conventional three-wave mixing parametric amplification or difference frequency generation. We argue that the nonlinear frequency convertor based on cascaded difference frequency generation is promising for achieving efficient and robust frequency conversion.
Optical singularity assisted method for accurate parameter detection of step-shaped nanostructure in coherent Fourier scatterometry
Authors: Dou Xiujie , Min Changjun , Zhang Yuquan , Pereira S. F. , Yuan Xiaocong
Published: July 2022

Accurate determination of the physical parameters of nanostructures from optical far-field scattering is an important and challenging topic in the semiconductor industry. Here, we propose a novel metrology method to determine simultaneously the height and side-wall angle of a step-shaped silicon nanostructure. By employing an optical singular beam into a typical coherent Fourier scatterometry system, both parameters can be retrieved through analyzing the intensity profile of the far-field scattering pattern. The use of singular beam is shown to be sensitive to slight changes of the parameters of the step. By changing the relative direction between the singularity and structure, the height and side-wall angle can both be retrieved with high precision. This new method is robust, simple, and can provide valuable means for micro-and-nano- metrologies.
Improvement of angle random walk of fiber-optic gyroscope using polarization-maintaining fiber ring resonator
Authors: Liu Yishi , Luo Xiaowan , Chen Xingfan
Published: July 2022

For an interferometric fiber-optic gyroscope (IFOG), the angle random walk, which represents the sensitivity of rotation detection, is mainly limited by the relative intensity noise (RIN) of a broadband source. Using a single-mode fiber ring resonator (SM-FRR) to filter the spectrum of a broadband light source is a common strategy for reducing the RIN at the proper IFOG frequency. However, this method depends on the polarization cross-coupling within the SM-FRR. We model the effect of polarization cross-coupling on the SM-FRR. Then, to further reduce the RIN, we introduce a polarization-maintaining fiber ring resonator (PM-FRR), which mitigates the effect of polarization cross-coupling on the SM-FRR. Using the PM-FRR as a spectrum filter, the RIN is reduced to –143 dB/Hz, with a reduction ratio of 25 dB, and the angle random walk in the IFOG is improved by over five times from 1.17 to 0.223 mdeg/h1/2 using a 2.1 km sensing coil.
Highly efficient near-infrared light-emitting diodes based on Zn:CuInSe2/ZnS//ZnS quantum dots with double shell engineering
Authors: Zhang Xuhui , Wang Tianyue , Lin Qingli , Chen Fei , Wang Lei , Du Zuliang
Published: July 2022

Near-infrared (NIR) quantum dot-based light-emitting diodes (QLEDs) developed rapidly in the fields of biomedical applications, telecommunications, sensing and diagnostics. However, it remains an enormous challenge for the synthesis of high-quality NIR QD materials with low toxicity or non-toxicity, high photoluminescence (PL) quantum yields (QYs) and high stability. Herein, we used a facile method to synthesize large-sized (8 nm) and thick-shell NIR Zn:CuInSe2/ZnS//ZnS QDs by engineering a double ZnS shell. The resulting NIR QDs exhibited high PL QYs of 80%, and excellent photochemical stability, which could be ascribed to the decreased lattice mismatch of the core/shell interface by the introduced Zn element into CuInSe2 cores and the energetic defect passivation of the double ZnS shell engineering. Furthermore, the high-quality Zn:CuInSe2/ZnS//ZnS QDs based LEDs exhibited the maximum external quantum efficiency (EQE) of 3.0%, 4.0% and 2.5% for PL peaks located at 705, 719 and 728 nm, respectively. This efficiency is comparable to that of the outstanding PbS- and InAs-based NIR QLEDs, as well as the avoidance of toxic heavymetal and/or hazardous reagents in this work. The synthesized high-quality Zn:CuInSe2/ZnS//ZnS QDs could be expected to promote the potential applications of heavy-metal-free QDs in the NIR fields.
Self-powered p-CuI/n-GaN heterojunction UV photodetector based on thermal evaporated high quality CuI thin film
Authors: Zhou Zhiying , Zhao Fengzhou , Wang Cheng , Li Xiaoxuan , He Shunli , Tian Dan , Zhang Dengying , Zhang Lichun
Published: July 2022

With vacuum thermal evaporation, the CuI film was deposited on quartz and n-GaN substrates, and the morphology, crystalline structure and optical properties of the CuI films were investigated. According to the XRD results, the CuI film preferentially grew along [111] crystal orientation on the GaN epilayer. With Au and Ni/Au ohmic contact electrodes fabricated on CuI and n-GaN, a prototype p-CuI/n-GaN heterojunction UV photodetector strong UV spectral selectivity was created. At 0 V and 360 nm front illumination (0.32 mW/cm2), the heterojunction photodetector displayed outstanding self-powered detection performance with the responsivity (R), specific detectivity (D*), and on/off ratio up to 75.5 mA/W, 1.27×1012 Jones, and ∼2320, respectively. Meanwhile, the p-CuI/n-GaN heterojunction photodetector had excellent atmosphere stability.
Design and collaborative optimization method of multilayer coatings to correct polarization aberration of optical systems
Authors: Jia Wentao , He Wenjun , Li Yahong , Fu Yuegang , Zhang Lei
Published: July 2022

Multilayer coatings induce a significant polarization aberration in optical systems with high numerical aperture (NA) and wide field of view, which will cause wavefront distortion and imaging degradation. Studies have used low-polarization coatings (LPC) design to reduce the coating-induced polarization aberration. However, the polarization aberration caused by LPC remain evident in systems with large incident angles and many coated surfaces. In this paper, a hybrid optimization algorithm (HOA) is proposed to enhance the design accuracy of LPC. Based on the HOA, a collaborative optimization method is developed to simultaneously design coatings with different polarization properties for multiple surfaces, which can correct polarization aberration by mutual compensation between the coated surfaces and other optical elements in a single system. Finally, a high NA lithographic lens is simulated as an example to verify the collaborative optimization method. The simulation demonstrates that this method is superior to conventional methods. This research provides a new way to correct the polarization aberration and is applicable to any systems coated with multilayer coatings.
Design and optimization of a passive PT-symmetric grating with asymmetric reflection and diffraction
Authors: Zheng Shuang , Yu Weizhen , Zhang Weifeng
Published: July 2022

In recent years, notions drawn from non-Hermitian physics and parity-time (PT) symmetry have raised considerable attention in photonics, enabling various novel structures with entirely new and unexpected features. Here we propose, design, and optimize a compact passive PT-symmetric grating to achieve asymmetric reflection and diffraction based on a silicon-on-insulator (SOI) platform. The structure is composed of two sets of interleaved tailored gratings, which are all well-defined on the top of a silicon waveguide. Without additional loss or gain materials, the effective index and the scattering loss of the waveguide mode are modulated by the structure design. To our knowledge, it is the first time that the scattering loss arising from grating elements is regarded as an efficient way to realize PT-symmetric structure. The complicated multi-parameter optimization process of the proposed PT-symmetric grating is completed by using the particle swarm optimization (PSO) algorithm. In the simulation, asymmetric reflection with high contrast ratio is realized. We also find that the waveguide-to-free-space diffraction from one side of the structure is significantly suppressed, leading to asymmetric diffraction. Moreover, we investigate the fabrication tolerance of the proposed PT-symmetric grating. Our work provides a new perspective for exploring and creating complicated on-chip PT-symmetric devices.
9.14-Mbps 64-PPM UWOC system based on a directly modulated MOPA with pre-pulse shaping and a high-sensitivity PMT with analog demodulation
Authors: Zhang Chao , Yang Xingqi , Zou Haiwu , Zhang Hao , Zhang Yufan , Dai Yizhan , Song Guangbin , Zhang Zejun , Wu Bo , Xu Jing
Published: July 2022

A pulsed fiber master oscillator power amplifier (MOPA), which is combined with second harmonic generation (SHG) and modulated by directly changing the current of the low-power seed laser, is designed in this paper to overcome the ‘green gap’ of semiconductor lasers and the difficulty of obtaining high-power and wide-bandwidth driving circuits. To decrease the guard slot and increase the data rate of a high-order pulse position modulation (PPM) system, pre-pulse shaping (PPS) is utilized to decrease the fluctuation of pulse power, which is caused by the gain dynamics of multi-order amplification of the MOPA, from 55.6% to 27.5% for 25-ns pulses and from 22.4% to 16.7% for 10-ns pulses, respectively. Moreover, an analog PPM demodulation method is proposed to mitigate the nonlinear effect caused by space charge limitations at dynodes of a photomultiplier tube (PMT) and increase the robustness of the system. In an optical darkroom, a 99-m 64-PPM UWOC transmission, of which the measured link loss is around 13.16 attenuation length (AL), is realized in a water tank with a data rate of 9.14 Mbps. The average received optical power ranges from −60.87 to −52.51 dBm, corresponding to a bit error rate (BER) range of 1.93 × 10−4 to 2.3 × 10−3. To further prove the reliability of the proposed system, we implement a 65-m UWOC experiment with the same data rate at a BER of 3.42 × 10−4 in a 50-m standard swimming pool. The maximum link loss is measured to be 15 AL.
Coscinodiscus diatom inspired bi-layered photonic structures with near-perfect absorptance Part II: hexagonal vs. square lattice-based structures
Authors: Hassan Mohammad Muntasir , Zaman Sameia , Hasanuzzaman M. , Baten Md Zunaid
Published: July 2022

In this follow up of our previous work on bio-inspired photonics [Opt. Express 28, 25007 (2020)10.1364/OE.399505], we present a detailed comparison between the absorption characteristics of hexagonal and square lattice oriented bi-layered photonic structures designed based on the morphology of Coscinodiscus diatom. It is well established that single layers of square lattice-based systems offer better light absorption characteristics than their hexagonal counterparts. However this study shows that superior performances are obtained with hexagonal lattices when bi-layered photonic structures mimicking Coscinodiscus diatom are designed. The finite difference time domain and effective medium approximation based numerical analysis of this work show that bi-layered structures containing hexagonal lattices exhibit tunable, near-perfect (∼95%) absorptance at around 426 nm wavelength up to about 60° angle of incidence, whereas for square lattice the absorptance goes below 85% (65%) for TM (TE) polarization. Moreover, depending on whether light is being incident onto smaller or larger pores of the bi-layered system, peak absorptance for hexagonal lattices is obtained to be nearly 4 times higher than the results obtained for the equivalent square lattices. Such characteristics make the hexagonal lattice-based structures more suitable for bi-facial light absorption related applications.
Probabilistic shaped 128-APSK CV-QKD transmission system over optical fibres
Authors: Pereira Daniel , Almeida Margarida , Facão Margarida , Pinto Armando N. , Silva Nuno A.
Published: July 2022

In this Letter we present a discrete modulated, continuous variables quantum key distribution implementation using two probabilistically shaped, 128-symbol, amplitude and phase shift keying constellations. At Bob’s detection side, a polarization diverse, true heterodyne receiver architecture is implemented for symbol recovery. We demonstrate experimentally that our system is capable of achieving security against collective attacks, while using accessible, telecom-grade material, and of functioning for an indefinitely long period of time at distances in excess of 185 km, in the asymptotic regime.
Super-resolved discrimination of nanoscale defects in low-dimensional materials by near-field photoluminescence spectral imaging
Authors: Huang Jiatai , Cui Tong , Sun Jia-Lin , Bai Benfeng , Sun Hong-Bo
Published: July 2022

Low-dimensional materials (LDMs), such as monolayer transition-metal dichalcogenides, have emerged as candidate materials for next-generation optoelectronics devices. Detection of the spatial heterogeneity caused by various nanoscale defects in LDMs, is crucial for their applications. Here, we report the super-resolved discrimination of various nanoscale defects in LDMs by near-field photoluminescence (NFPL) spectral imaging of LDMs with scanning near-field optical microscopy. As a demonstration example, a monolayer WS2 sample is characterized with a sub-diffraction spatial resolution of 140 nm in ambient environment. By performing topography and NFPL mapping, different defects, such as the stacks, bubbles, and wrinkles, can be identified through their light emission properties, which strongly correlate with the exciton emission modulation and tensile strain arising from local structural deformations.
Robust site-resolved addressing via dynamically tracking the phase of optical lattices
Authors: Zheng Yong-Guang , Zhu Zi-Hang , Liu Ying , Zhang Wei-Yong , Wang Han-Yi , Yu Song-Tao , Luo An , Sun Hui , Yuan Zhen-Sheng , Pan Jian-Wei
Published: July 2022

Single-site-resolved addressing offers an unprecedented capability of manipulating atoms in optical lattices. We demonstrate a robust site-resolved addressing by locking the position of the addressing beam to the optical lattice phase. The addressing beam is modulated by a digital micromirror device (DMD) integrated into a quantum gas microscope (QGM). A typical experiment with ultracold atoms takes several hours to collect hundreds of samples by repeating the sequence of programmed operations, whose duration is 40 seconds. During the collection, the phase of optical lattices can drift over a few lattice sites. According to the phases of the lattice obtained from the current experimental realizations, we correct the addressing beam position for the subsequent realization by shifting the pattern of the activated micromirrors on the DMD. This feedback loop is compiled to an application with a graphical user interface (GUI) for relevant devices, which is synchronized to the experimental sequence. The long-term (5 hours) position deviation between the pointing of the addressing beam and the lattice phase is suppressed to a 0.02(2)/0.02(2) lattice spacing in the X/Y direction, verifying a 10-fold reduction in comparison to that without feedback. With the help of phase-locking, the success rate of site-resolved addressing is improved substantially from 60(7)% to 95(2)%.
Spectral purification of single-frequency Stokes pulses in doubly resonant integrated diamond resonators
Authors: Granados Eduardo , Stoikos Georgios
Published: July 2022

Pulsed spectrally pure light is required for applications in high-resolution spectroscopy, optical coherent communications, and quantum technologies. In this work, we report on the efficient generation of high peak power, single-frequency, and tunable nanosecond pulses utilizing stimulated scattering, with an increased spectral brightness by exploiting double resonances in an integrated diamond Raman resonator. The device is based on a miniature monolithic Fabry–Perot design pumped by a milliwatt-class average power Q-switched single-frequency pulsed laser at 532 nm. Our device was capable of enhancing the peak spectral brightness by greater than three times compared with conventional singly resonant diamond Raman lasers by tuning the effective resonator length at pump and Stokes wavelengths simultaneously. Our results facilitate the integration of pulsed and power scalable single frequency sources into hybrid photonic integrated platforms with a broad range of applications.
OFDM-PS-256QAM signal delivery at 47.45 Gb/s over 4.6-kilometers wireless distance at the W band
Authors: Li Weiping , Yu Jianjun , Wang Yanyi , Wang Feng , Zhu Bowen , Zhao Li , Zhou Wen , Yu Jianguo , Zhao Feng
Published: July 2022

Photonics technology is a promising way to generate high-frequency millimeter waves, which is also a key technology to realize the convergence of fiber-optic and wireless communication. To meet the actual application requirements, kilometer-level wireless distance, large-capacity, and high-spectral-efficiency systems are urgent requirements. Based on the photonics-aided system at the W band, we achieve a net rate of 47.45-Gb/s signal delivery over a 10-km single-mode fiber-28 (SMF-28) and 4.6-km wireless free-space link. The spectral efficiency of the system is 4.97 bit/s/Hz. To the best of our knowledge, this is the first demonstration at more than a 4-km wireless distance level at the W band based on a photonics-aided system, and we achieve a record product of the single-channel transmission rate and wireless distance, i.e., 47.45 Gb/s × 4.6 km = 218.27 Gb/s km. The experimental results provide a good reference value for improving the transmission distance and data rate of the radio-over-fiber (ROF) system, and will play an important role in the future beyond the 5G era.
High-power multi-wavelength Yb-doped fiber laser with a tunable interval, amplitude, and a number of channels
Authors: Li Sicheng , Xu Jiangming , Liang Junrui , Ye Jun , Zhang Yang , Ma Xiaoya , Zhou Pu
Published: July 2022

In recent years, multi-wavelength lasers have attracted much attention due to their wide applications in various fields. In this Letter, we experimentally demonstrate a high-power multi-wavelength Yb-doped fiber laser with the aid of an acoustic-optic tunable filter, in which the wavelength interval, the intensity of each channel, and the number of lasing channels can be tuned independently. As a result, the operating wavelength tuning range covers 1040.0 to 1090.0 nm and the maximal output power reaches 15.7 W, which is higher than the previous reports by more than three orders of magnitude. The wavelength interval can be adjusted from 2.6 to 50 nm and the spectral profile can be arbitrarily controlled. Furthermore, the number of wavelength channels can be adjusted from 1 to 4. This work will provide a reference for achieving high-power spectral-flexible fiber sources.
Error-resistant nonadiabatic binomial-code geometric quantum computation using reverse engineering
Authors: Kang Yi-Hao , Song Jie , Xia Yan
Published: July 2022

We propose a scheme to realize error-resistant nonadiabatic binomial-code geometric quantum computation using reverse engineering. A strong Kerr nonlinearity restricts the evolution in a computational subspace of the binomial code and a two-photon squeezing drive provides the connections between the logical states. The effective Hamiltonian possesses SU(2) dynamic structure and is analyzed through reverse engineering based on a dynamic invariant. By combining reverse engineering with the optimal control method, we find the evolution paths for nonadiabatic geometric quantum computation and derive the control field robust against the systematic error. Numerical simulations show that the scheme holds excellent resistance to the systematic error and is still well implemented in the presence of resonator leakage with the current superconducting nonlinear resonator technology. Therefore, the scheme may provide a promising approach for accurate nonadiabatic binomial-code geometric quantum computation.
High-power wavelength-tunable and power-ratio-controllable dual-wavelength operation at 1319  nm and 1338  nm in a Q-switched Nd:YAG laser
Authors: Bian Qi , Bo Yong , Zuo Jun-Wei , Yuan Lei , Gao Hong-Wei , Peng Qin-Jun
Published: July 2022

We report the first demonstration on three types of 1.3 μm spectral region in a

Q

-switched Nd:YAG laser. In order to dissipate the heat deposition effectively to obtain good beam quality, the Nd:YAG rod crystal with 1° cut-angle on end faces is side-pumped by the quasi-continuous-wave pulsed laser diode. A Suprasil etalon is well designed as the intracavity mode-selector to obtain wavelength-tunable single line or power-ratio-controllable dual line operation at 1319 nm and 1338 nm. With the pump pulse width of 200 μs and pump power of 410 W, the acousto-optic

Q

-switched laser delivered a pulse width of 117 ns at 400 Hz repetition rate, and the

M
2

factor was measured to be about 1.87. 1319 nm together with 1338 nm single-wavelength laser achieved an average output power of 47.6 W and 39.9 W with a linewidth of 0.48 nm and 0.32 nm, and a tunable range of 111.2 pm and 108.6 pm, respectively. Among dual-wavelength oscillation, both lines can be tuned at almost equal intensity level with 45.7 W total output power, which is input into an LBO crystal to generate red light of 11.4 W for 659 nm, 6.7 W for 664 nm, and 7.5 W for 669 nm. The 1.3 μm wavelength-selectable operation realized by using the same laser configuration may enhance the application in the fields of tunable lasers and THz frequency generation.
Metasurface for oscillatory spin splitting along the optical path
Authors: Li Yu , Fan Xinhao , Guo Xuyue , Zhang Yi , Liu Sheng , Wei Bingyan , Wen Dandan , Li Peng , Zhao Jianlin
Published: July 2022

Spin splitting of light originates from the interplay between the polarization and spatial degrees of freedom as a fundamental constituent of the emerging spin photonics, providing a prominent pathway for manipulating photon spin and developing exceptional photonic devices. However, previously relevant devices were mainly designed for routing monotonous spin splitting of light. Here, we realize an oscillatory spin splitting of light via metasurface with two channel Pancharatnam–Berry phases. For the incidence of a linearly polarized light, the concomitant phases arising from opposite spin states transition within pathways of the metasurface induce lateral spin splitting of light with alternately changed transport direction during beam guiding. We demonstrate the invariance of this phenomenon with an analogous gauge transformation. This work provides a new insight on steering the photon spin and is expected to explore a novel guiding mechanism of relativistic spinning particles, as well as applications of optical trapping and chirality sorting.
Modulation transfer functions for audiovisual speech
Authors: Pedersen Nicolai F. , Dau Torsten , Hansen Lars Kai , Hjortkjær Jens
Published: July 2022

Temporal synchrony between facial motion and acoustic modulations is a hallmark feature of audiovisual speech. The moving face and mouth during natural speech is known to be correlated with low-frequency acoustic envelope fluctuations (below 10 Hz), but the precise rates at which envelope information is synchronized with motion in different parts of the face are less clear. Here, we used regularized canonical correlation analysis (rCCA) to learn speech envelope filters whose outputs correlate with motion in different parts of the speakers face. We leveraged recent advances in video-based 3D facial landmark estimation allowing us to examine statistical envelope-face correlations across a large number of speakers (∼4000). Specifically, rCCA was used to learn modulation transfer functions (MTFs) for the speech envelope that significantly predict correlation with facial motion across different speakers. The AV analysis revealed bandpass speech envelope filters at distinct temporal scales. A first set of MTFs showed peaks around 3-4 Hz and were correlated with mouth movements. A second set of MTFs captured envelope fluctuations in the 1-2 Hz range correlated with more global face and head motion. These two distinctive timescales emerged only as a property of natural AV speech statistics across many speakers. A similar analysis of fewer speakers performing a controlled speech task highlighted only the well-known temporal modulations around 4 Hz correlated with orofacial motion. The different bandpass ranges of AV correlation align notably with the average rates at which syllables (3-4 Hz) and phrases (1-2 Hz) are produced in natural speech. Whereas periodicities at the syllable rate are evident in the envelope spectrum of the speech signal itself, slower 1-2 Hz regularities thus only become prominent when considering crossmodal signal statistics. This may indicate a motor origin of temporal regularities at the timescales of syllables and phrases in natural speech.