High-efficiency ultra-fast all-optical photonic crystal diode based on the lateral-coupled nonlinear elliptical defect

An all-optical Fano-like diode featuring a nonlinear lateral elliptical micro-cavity and a reflecting column in the photonic crystal waveguide is proposed.The asymmetric micro-cavity is constructed by removing one rod and changing the shape of the lateral rod from a circle to an ellipse.A reflecting pillar is also introduced into the waveguide to construct an F-P cavity with the elliptical defect and enhance the asymmetric transmission for the incident light wave transmitting rightwards and leftwards,respectively.By designing the size of the ellipse and optimizing a reflecting rod at a suitable position,a maximum forward light transmittance of-1.14 dB and a minimum backward transmittance of-57.66 dB are achieved at the working wavelength of 1550.47 nm.The corresponding response time is about 10 ps when the intensity of the pump light beam resonant at 637 nm is 3.97 W/μm2.

High-performance chiral all-optical OR logic gate based on topological edge states of valley photonic crystal

For all-optical communication and information processing,it is necessary to develop all-optical logic gates based on photonic structures that can directly perform logic operations.All-optical logic gates have been demonstrated based on conventional waveguides and interferometry,as well as photonic crystal structures.Nonetheless,any defects in those structures will introduce high scattering loss,which compromises the fidelity and contrast ratio of the information process.Based on the spin-valley locking effect that can achieve defect-immune unidirectional transmission of topological edge states in valley photonic crystals(VPCs),we propose a high-performance all-optical logic OR gate based on a VPC structure.By tuning the working bandwidth of the two input channels,we prevent interference between the two channels to achieve a stable and high-fidelity output.The transmittance of both channels is higher than 0.8,and a high contrast ratio of 28.8 dB is achieved.Moreover,the chirality of the logic gate originated from the spin-valley locking effect allows using different circularly polarized light as inputs,representing“1”or“0”,which is highly desired in quantum computing.The device’s footprint is 18μm×12μm,allowing high-density on-chip integration.In addition,this design can be experimentally fabricated using current nanofabrication techniques and will have potential applications in optical communication,information processing,and quantum computing.

基于Relay的低成本4G网络覆盖增强方法

无缝覆盖是无线移动通信网络的重要特点之一。对于人烟稀少地区,比如海面,沙漠等场景,需要进行低成本的超远无线通信覆盖。但是,如果单纯地通过架设基站满足这类超远覆盖会增加运营商的基站造价成本。文章分析比较4G网络的覆盖增强部署方法,提出基于Relay的低成本覆盖增强方法。其核心思想是:根据4G网络覆盖范围要求,部署4G网络中继节点,确定网络基站和中继节点之间无线通信的最少上行子帧个数。同时,结合4G无线移动通信系统模式确定可选的中继部署类型和配置,从而实现低成本、高质量的4G网络增强覆盖。

An all-optical time-delay relay based on a bacteriorhodopsin film

Using a special property of dynamic complementary-suppression-modulated transmission （DCSMT） in the bacteriorhodopsin （bR） film, we have demonstrated an all-optical time-delay relay. To extend our work, the relationship between the delay time of the all-optical time-delay relay and parameters of a bR film is numerically studied. We show how the delay time changes with the product of concentration and thickness （PCT） of a bR film. Furthermore, the shortest and longest delay times are given for the relay of ＇switch off. The saturable delay time and maximum delaytime of ＇switch on＇ are also given. How the wavelengths （632.8, 568, 533 and 412 nm） and intensities of the illuminating light influence the delay time is also discussed. The simulation results are useful for optimizing the design of all-optical time-delay relays.

Optimization of Cooperative RelayingMolecular Communications for Nanomedical Applications

Recently,nano-systems based on molecular communications via diffusion(MCvD)have been implemented in a variety of nanomedical applications,most notably in targeted drug delivery system(TDDS)scenarios.Furthermore,because the MCvD is unreliable and there exists molecular noise and inter symbol interference(ISI),cooperative nano-relays can acquire the reliability for drug delivery to targeted diseased cells,especially if the separation distance between the nano transmitter and nano receiver is increased.In this work,we propose an approach for optimizing the performance of the nano system using cooperative molecular communications with a nano relay scheme,while accounting for blood flow effects in terms of drift velocity.The fractions of the molecular drug that should be allocated to the nano transmitter and nano relay positioning are computed using a collaborative optimization problem solved by theModified Central Force Optimization(MCFO)algorithm.Unlike the previous work,the probability of bit error is expressed in a closed-form expression.It is used as an objective function to determine the optimal velocity of the drug molecules and the detection threshold at the nano receiver.The simulation results show that the probability of bit error can be dramatically reduced by optimizing the drift velocity,detection threshold,location of the nano-relay in the proposed nano system,and molecular drug budget.

Coordinated responses of leaf and nodule traits contribute to the accumulation of N in relay intercropped soybean

Maize(Zea mays L.)-soybean(Glycine max L.Merr.)relay intercropping provides a way to enhance land productivity.However,the late-planted soybean suffers from shading by the maize.After maize harvest,how the recovery growth influences the leaf and nodule traits remains unclear.A three-year field experiment was conducted to evaluate the effects of genotypes,i.e.,supernodulating(nts1007),Nandou 12(ND12),and Guixia 3(GX3),and crop configurations,i.e.,the interspecific row spacing of 45(I45),60(I60),75 cm(I75),and sole soybean(SS),on soybean recovery growth and N fixation.The results showed that intercropping reduced the soybean total leaf area(LA)by reducing both the leaf number(LN)and unit leaflet area(LUA),and it reduced the nodule dry weight(NW)by reducing both the nodule number(NN)and nodule diameter(ND)compared with the SS.The correlation and principal component analysis(PCA)indicated a co-variability of the leaf and nodule traits in response to the genotype and crop configuration interactions.During the recovery growth stages,the compensatory growth promoted soybean growth to reduce the gaps of leaf and nodule traits between intercropping and SS.The relative growth rates of ureide(RGR_U)and nitrogen(RGR_N)accumulation were higher in intercropping than in SS.Intercropping achieved more significant sucrose and starch contents compared with SS.ND12 and GX3 showed more robust compensatory growth than nts1007 in intercropping.Although the recovery growth of relay intercropping soybean improved biomass and nitrogen accumulation,ND12 gained a more significant partial land equivalent ratio(pLER)than GX3.The I60 treatment achieved more robust compensation effects on biomass and N accumulation than the other configurations.Meanwhile,I60 showed a higher nodule sucrose content and greater shoot ureide and N accumulation than SS.Finally,intercropping ND12 with maize using an interspecific row spacing of 60 cm was optimal for both yield advantage and N accumulation.

System design and validation of Queqiao-2 lunar relay communication satellite

In order to provide relay communication supports for future Chinese lunar exploration program,Queqiao-2 relay communication satellite was developed.Queqiao-2 can perform scientific observations with three kinds of scientific instruments on board.The system design of Queqiao-2,including mission orbit and transfer orbit design,configuration and layout design,housekeeping and information flow design,power supply and distribution design,GNC and propulsion system design,communication links design,etc.,was accomplished through comprehensive tradeoff and evaluation on technical maturity,availability,schedule,cost,and so on.With a view to reducing development risk,both the platform and relay communication payloads were developed based on significant heritage from previous Queqiao relay satellite and other relevant spacecraft.Queqiao-2 features flexible system architecture to support multiple frequencies,modulations,data rates and software reconfigurations to meet new user requirements.Subsequent to a successful launch on March 20,2024,by means of 5 orbit maneuvers,Queqiao-2 was inserted into a highly elliptical frozen mission orbit around the moon with a 24h period on schedule.Following on-orbit tests and calibrations,Queqiao-2 has possessed the capacity to provide reliable relay communication services to multiple lunar exploration missions,as well as the capacity to perform scientific observations.Under the support of Queqiao-2,Chang′e-6 achieved its ambitious mission goal to collect and return samples from the moon′s mysterious far side.In the meanwhile,Queqiao-2 has also paved the way for the following Chinese lunar exploration missions including Chang′e-7 and Chang′e-8.The design life time of Queqiao-2 is more than 8 years.Benefit from flexibility and extensibility of relay communication system design,it is convenient to provide relay communication services for future lunar exploration missions of both China and other countries.In addition,innovative scientific observations would be performed during the period that no relay communication task is arranged.The system design of Queqiao-2 reflects the development philosophy of technical innovations and inheritance integration.Based on highly flexible and extensible system architecture,multiple and concurrent relay communication mission requirements can be met.It can provide strong supports for future lunar exploration missions.Successful launching,orbit entering and on-orbit tests of Queqiao-2 verified the correct design principle and versatility.By means of Queqiao-2,more innovative scientific outcomes are anticipated and lunar exploration activities can be facilitated.

A Pricing-Based Cooperative Relay Selection Scheme for Reliable Communications

With the rapid development and application of energy harvesting technology,it has become a prominent research area due to its significant benefits in terms of green environmental protection,convenience,and high safety and efficiency.However,the uneven energy collection and consumption among IoT devices at varying distances may lead to resource imbalance within energy harvesting networks,thereby resulting in low energy transmission efficiency.To enhance the energy transmission efficiency of IoT devices in energy harvesting,this paper focuses on the utilization of collaborative communication,along with pricing-based incentive mechanisms and auction strategies.We propose a dynamic relay selection scheme,including a ladder pricing mechanism based on energy level and a Kuhn-Munkre Algorithm based on an auction theory employing a negotiation mechanism,to encourage more IoT devices to participate in the collaboration process.Simulation results demonstrate that the proposed algorithm outperforms traditional algorithms in terms of improving the energy efficiency of the system.

Security-Reliability Tradeoff Analysis for Jamming Aided Decode-and-Forward Relay Networks

In this paper,we explore a cooperative decode-and-forward(DF)relay network comprised of a source,a relay,and a destination in the presence of an eavesdropper.To improve physical-layer security of the relay system,we propose a jamming aided decodeand-forward relay(JDFR)scheme combining the use of artificial noise and DF relaying which requires two stages to transmit a packet.Specifically,in stage one,the source sends confidential message to the relay while the destination acts as a friendly jammer and transmits artificial noise to confound the eavesdropper.In stage two,the relay forwards its re-encoded message to the destination while the source emits artificial noise to confuse the eavesdropper.In addition,we analyze the security-reliability tradeoff(SRT)performance of the proposed JDFR scheme,where security and reliability are evaluated by deriving intercept probability(IP)and outage probability(OP),respectively.For the purpose of comparison,SRT of the traditional decode-and-forward relay(TDFR)scheme is also analyzed.Numerical results show that the SRT performance of the proposed JDFR scheme is better than that of the TDFR scheme.Also,it is shown that for the JDFR scheme,a better SRT performance can be obtained by the optimal power allocation(OPA)between the friendly jammer and user.

Improving throughput in SWIPT-based wireless multirelay networks with relay selection and rateless codes

This paper studies a dual-hop Simultaneous Wireless Information and Power Transfer(SWIPT)-based multi-relay network with a direct link.To achieve high throughput in the network,a novel protocol is first developed,in which the network can switch between a direct transmission mode and a Single-Relay-Selection-based Cooperative Transmission(SRS-CT)mode that employs dynamic decode-and-forward relaying accomplished with Rateless Codes(RCs).Then,under this protocol,an optimization problem is formulated to jointly optimize the network operation mode and the resource allocation in the SRS-CT mode.The formulated problem is difficult to solve because not only does the noncausal Channel State Information(CSI)cause the problem to be stochastic,but also the energy state evolution at each relay is complicated by network operation mode decision and resource allocation.Assuming that noncausal CSI is available,the stochastic optimization issue is first to be addressed by solving an involved deterministic optimization problem via dynamic programming,where the complicated energy state evolution issue is addressed by a layered optimization method.Then,based on a finite-state Markov channel model and assuming that CSI statistical properties are known,the stochastic optimization problem is solved by extending the result derived for the noncausal CSI case to the causal CSI case.Finally,a myopic strategy is proposed to achieve a tradeoff between complexity and performance without the knowledge of CSI statistical properties.The simulation results verify that our proposed SRS-and-RC-based design can achieve a maximum of approximately 40%throughput gain over a simple SRS-and-RC-based baseline scheme in SWIPT-based multi-relay networks.

Beamforming Design for IRS-and-UAV-Aided Two-Way Amplify-and-Forward Relay Networks in Maritime IoT

In this paper,an intelligent reflecting surface(IRS)-and-unmanned aerial vehicle(UAV)-assisted two-way amplify-and-forward(AF)relay network in maritime Internet of Things(IoT)is proposed,where ship1(S1)and ship2(S2)can be viewed as data collecting centers.To enhance the message exchange rate between S1 and S2,a problem of maximizing minimum rate is cast,where the variables,namely AF relay beamforming matrix and IRS phase shifts of two time slots,need to be optimized.To achieve a maximum rate,a low-complexity alternately iterative(AI)scheme based on zero forcing and successive convex approximation(LC-ZF-SCA)algorithm is presented.To obtain a significant rate enhancement,a high-performance AI method based on one step,semidefinite programming and penalty SCA(ONSSDP-PSCA)is proposed.Simulation results show that by the proposed LC-ZF-SCA and ONS-SDP-PSCA methods,the rate of the IRS-and-UAV-assisted AF relay network surpass those of with random phase and only AF relay networks.Moreover,ONS-SDP-PSCA perform better than LC-ZF-SCA in aspect of rate.

Designing a Protection Scheme in Micro-Grid Systems with DG Using Central Protection Unite and Multiple Setting Group Protection Relays

Distributed generators now is widely used in electrical power networks, in some cases it works seasonally, and some types works at special weather conditions like photo voltaic systems and wind energy, and due to this continuous changes in generation condition, the fault current level in network will be affected, this changes in fault current level will affect in the coordination between protection relays and to keep the coordination at right way, an adaptive protection system is required that can adaptive its setting according to generation changes, the fault current level in each case is evaluated using ETAP software, and the required relay setting in each case is also evaluated using Grey Wolf Optimizer (GWO) algorithm, and to select suitable setting which required in each condition, to select the active setting group of protection relay according to generation capacity, central protection unite can be used, and to improve protection stability and minimizing relays tripping time, a proposed method for selecting suitable backup relay is used, which leads to decrease relays tripping time and increase system stability, output settings for relays in all cases achieved our constrains.

Security-Reliability Analysis and Optimization for Cognitive Two-Way Relay Network with Energy Harvesting

This paper investigates the security and reliability of information transmission within an underlay wiretap energy harvesting cognitive two-way relay network.In the network,energy-constrained secondary network(SN)nodes harvest energy from radio frequency signals of a multi-antenna power beacon.Two SN sources exchange their messages via a SN decode-and-forward relay in the presence of a multiantenna eavesdropper by using a four-phase time division broadcast protocol,and the hardware impairments of SN nodes and eavesdropper are modeled.To alleviate eavesdropping attacks,the artificial noise is applied by SN nodes.The physical layer security performance of SN is analyzed and evaluated by the exact closed-form expressions of outage probability(OP),intercept probability(IP),and OP+IP over quasistatic Rayleigh fading channel.Additionally,due to the complexity of OP+IP expression,a self-adaptive chaotic quantum particle swarm optimization-based resource allocation algorithm is proposed to jointly optimize energy harvesting ratio and power allocation factor,which can achieve security-reliability tradeoff for SN.Extensive simulations demonstrate the correctness of theoretical analysis and the effectiveness of the proposed optimization algorithm.

Average Secrecy Capacity of the Reconfigurable Intelligent Surface-Assisted Integrated Satellite Unmanned Aerial Vehicle Relay Networks

Integrated satellite unmanned aerial vehicle relay networks(ISUAVRNs)have become a prominent topic in recent years.This paper investigates the average secrecy capacity(ASC)for reconfigurable intelligent surface(RIS)-enabled ISUAVRNs.Especially,an eve is considered to intercept the legitimate information from the considered secrecy system.Besides,we get detailed expressions for the ASC of the regarded secrecy system with the aid of the reconfigurable intelligent.Furthermore,to gain insightful results of the major parameters on the ASC in high signalto-noise ratio regime,the approximate investigations are further gotten,which give an efficient method to value the secrecy analysis.At last,some representative computer results are obtained to prove the theoretical findings.

All-Optical Sampling Using Nonlinear Polarization Rotation in a Single Semiconductor Optical Amplifier

We propose a novel all-optical sampling method using nonlinear polarization rotation in a semiconductor optical amplifier. A rate-equation model capable of describing the all-optical sampling mechanism is presented in this paper. Based on this model, we investigate the optimized operating parameters of the proposed system by simulating the output intensity of the probe light as functions of the input polarization angle, the phase induced by the polarization controller, and the ori- entation of the polarization beam splitter. The simulated results show that we can obtain a good linear slope and a large linear dynamic range,which is suitable for all-optical sampling. The operating power of the pump light can be less than lmW. The presented all-optical sampling method can potentially operate at a sampling rate up to hundreds GS/s and needs low optical power.

Optically Digitalized Holography: A Perspective for All-Optical Machine Learning

Holography, which was invented by Dennis Gabor in 1948, offers an approach to reconstructing both the amplitude and phase information of a three-dimensional (3D) object [1]. Since its invention, the concept of holography has been widely used in various fields, such as microscopy [2], interferometry [3], ultrasonography [4], and holographic display [5]. Optical holography can be divided into two steps: recording and reconstruction. A conventional hologram is recorded onto a photosensitive film as the interference between an object beam carrying the 3D object information and a reference beam. Thereafter, the original object wavefront is reconstructed in the 3D image space by illuminating the reference beam on the recorded hologram.

All-optically integrated photoacoustic and optical coherence tomography:A review

All-optically integrated photoacoustic(PA)and optical coherence tomography(OCT)dualmode imaging technology that could o®er comprehensive pathological information for accurate diagnosis in clinic has gradually become a promising imaging technology in the aspect of biomedical imaging during the recent years.This review refers to the technology aspects of alloptical PA detection and system evolution of optically integrated PA and OCT,including Michelson interferometer dual-mode imaging system,Fabry–Perot(FP)interferometer dualmode imaging system and Mach–Zehnder interferometer dual-mode imaging system.It is believed that the optically integrated PA and OCT has great potential applications in biomedical imaging.

All-optical computing based on convolutional neural networks

The rapid development of information technology has fueled an ever-increasing demand for ultrafast and ultralow-en-ergy-consumption computing.Existing computing instruments are pre-dominantly electronic processors,which use elec-trons as information carriers and possess von Neumann architecture featured by physical separation of storage and pro-cessing.The scaling of computing speed is limited not only by data transfer between memory and processing units,but also by RC delay associated with integrated circuits.Moreover,excessive heating due to Ohmic losses is becoming a severe bottleneck for both speed and power consumption scaling.Using photons as information carriers is a promising alternative.Owing to the weak third-order optical nonlinearity of conventional materials,building integrated photonic com-puting chips under traditional von Neumann architecture has been a challenge.Here,we report a new all-optical comput-ing framework to realize ultrafast and ultralow-energy-consumption all-optical computing based on convolutional neural networks.The device is constructed from cascaded silicon Y-shaped waveguides with side-coupled silicon waveguide segments which we termed“weight modulators”to enable complete phase and amplitude control in each waveguide branch.The generic device concept can be used for equation solving,multifunctional logic operations as well as many other mathematical operations.Multiple computing functions including transcendental equation solvers,multifarious logic gate operators,and half-adders were experimentally demonstrated to validate the all-optical computing performances.The time-of-flight of light through the network structure corresponds to an ultrafast computing time of the order of several picoseconds with an ultralow energy consumption of dozens of femtojoules per bit.Our approach can be further expan-ded to fulfill other complex computing tasks based on non-von Neumann architectures and thus paves a new way for on-chip all-optical computing.

All-optical logic devices based on black arsenic-phosphorus with strong nonlinear optical response and high stability

The Kerr nonlinearity in two-dimensional(2D)nanomaterials is emerging as an appealing and intriguing research area due to their prominent light processing,modulation,and manipulation abilities.In this contribution,2D black arsenic-phosphorus(B-AsP)nanosheets(NSs)were applied in nonlinear photonic devices based on spatial self-phase modula-tion(SSPM)method.By applying the Kerr nonlinearity in 2D B-AsP,an all-optical phase-modulated system is proposed to realize the functions of“on”and“off”in all-optical switching.By using the same all-optical phase-modulated system,another optical logic gate is proposed,and the logical“or”function is obtained based on the 2D B-AsP NSs dispersions.Moreover,by using the SSPM method,a 2D B-AsP/SnS_(2) hybrid structure is fabricated,and the result illustrates that the hybrid structure possesses the ability of the unidirectional nonlinear excitation,which helps in obtaining the function of spatial asymmetric light propagation.This function is considered an important prerequisite for the realization of diode functionalization,which is believed to be a factor in important basis for the design of isolators as well.The initial investig-ations indicate that 2D B-AsP is applicable for designing optical logical devices,which can be considered as an import-ant development in all-optical information processing.

Mid-infrared supercontinuum generation and its application on all-optical quantization with different input pulses

Supercontinuum generation(SCG) and its application on all-optical quantization of all-optical analog-to-digital conversions(AOADCs) at the mid-infrared region in an Al GaAs strip waveguide are investigated numerically. The simulation results show that when the parabolic pulse is input, not only broader and higher-coherence SCG is obtained and a higher effective number of bits(ENOB) can be achieved, compared with the input pulse with hyperbolic-secant and Gaussian shaping. A four-bit quantization resolution is achieved along with a signal-to-noise ratio of 24.02 dB and an ENOB of3.99 bit, and the required input peak power is 760 mW.