Multichannel Transmission Research Articles

Programming Dual‐Color Circularly Polarized Luminescence with Self‐Organized Soft Photonic Helix

AbstractCircularly polarized light has the potential to significantly impact light–matter interactions and offers new opportunities and progresses for breakthroughs in various fields. Programming circularly polarized luminescence (CPL) with both multiple colors and high luminescence dissymmetry factor (glum) is a fantastic technique for photonic applications, such as information coding, high‐dimensional transmission, and CPL display. However, it is still a formidable challenge to balance the coupling between photonic bandgap (PBG) and material‐induced luminescence for achieving multi‐color CPL with high glum. Here a unique microcavity technology is reported that simultaneously allows for high glum and dual‐color when the broad PBG entirely overlaps the fluorescence peak and the bandedge is maintained within the fluorescent range. Benefitting from the programmable dual‐color CPL with tunable glum, an electric field‐responsive CPL display with contrast ratios up to 34:1 is successfully implemented. Furthermore, a multichannel switchable encoder prototype integrated with CPL is established to analogize an information encoding and multichannel transmission in a more convenient and less costly way. This work presents a novel platform for investigating chiral photonics and facilitates a deeper comprehension of light‐matter interactions in microcavity.

Multi-mode vortex beams generation with single-layer transmissive metasurface

Orbital angular momentum (OAM) is a phenomenon of vortex phase distribution in free space, the infinity of whose modes and the orthogonality between modes allow it to possess great potential in enhancing channel capacity. A transmissive metasurface consisting of a single-layer substrate and a two-layer metallic structure is proposed to enable vortex beam generation based on the concept of the Pancharatnam-Berry (PB) phase. The phase response is achieved by continuous phase modulation under circularly polarised (CP) wave incidence due to the simultaneous rotation of the upper and lower metal structures. Besides, through the introduction of both phase compensation on the metasurface and phase superposition of the beams to the array design, multi-beam generation is expected to be realized. A metasurface sample composed of 30 30 elements (450 mm 450 mm) is fabricated and measured in a microwave darkroom on the basis of the simulation results. Both the simulation and measurement results provide firm demonstration that the designed metasurface is capable of simultaneously generating four beams carrying OAM mode numbers of and different beam directions at the same aperture. The designed metasurface in this paper utilized for generating multi-mode vortex multi-beams will be of wide application in multi-channel transmission in wireless communication systems.

Six-element MIMO antenna structure with squared ring structure with multiband and high gain characteristics for C/X/Ku/K band applications

Using ring resonator structure, we have presented a structure of the six-element multiple input multiple output (MIMO) antenna structure. The proposed structure is numerically investigated and experimentally verified for antenna performance in the 1 to 25 GHz wideband frequency range. We have designed and verified the five antenna structure types, which consist of the various forms of ring/patch with different ground plane geometries. Various performance parameters like gain, directivity, reflections, and electric field distributions are analyzed for MIMO antennas. Essential performanceparameters observed for the MIMO antennas are also presented in this manuscript to identify the behaviour of the structure with different physical conditions. These parameters are also investigated for the identification of suitable ranges for the multi-channel transmission capability of the communication system. Return loss and Gain values are< −12 dB and ∼ 20 dBi achieved with ∼12 GHz of the operating bandwidth. Overall, the antenna offers minimum return loss values of −25 dB for the operating band of 19 to 25 GHz with anoperational bandwidth of 6 GHz. The designed antennas are tested using a ground patch and a rectangular patch in a scattered manner, and the obtained results are utilized in the Ultrawideband MIMO antenna applications. These antennas are also used in various band operations in satellite communication, including C/X/Ku/K bands.

Multi-channel data transmission through a multimode fiber based on OAM phase encoding.

Data transmission based on the transmission matrix method has realized the multiplexing of a large number of orbital angular momentum (OAM) modes under scattering, which encodes the data by modulating the amplitude of the OAM modes. However, this amplitude modulation (amplitude encoding) method has obvious cross talk when the number of output modes is small, resulting in a non-negligible bit error rate. Here, a multi-channel data transmission method based on OAM phase modulation (phase encoding) under scattering is proposed. This method can resist the multiple-scattering effect of multimode fibers and realize accurate data transmission with very few rows of camera pixels for output mode measurement, which is suitable for high-speed data transmission under scattering. Experimentally, we have achieved a bit error rate of less than 0.005% in the data transmission of a color image through a 60 m multimode fiber with only 2 rows of camera pixels for output mode measurement. Experiments also showed that the proposed method has a higher stability than amplitude encoding when the proportion of "1" or "0" in the code changes.

Characteristics of multi-channel intermuscular directional coupling based on time-varying partial directional coherence analysis

The human body transmits directional information between muscles during upper limb movements, and this will be particularly evident when the dominant muscle changes during movement transitions. By capturing the electromyography (EMG) signals of wrist flexion and extension continuous transition movements, we investigated the characteristics of multichannel intermuscular directional coupling and directional information transmission, and consequently explored the control mechanism of Central nervous system (CNS) and the coordination mechanism of motor muscles. Multi-channel EMG was collected from 12 healthy subjects under continuous translational movements of wrist flexion and extension, and the time-varying biased directional coherence analysis (TVPDC) model was constructed using partial directional coherence analysis (PDC) frequency domain directionality to study the directional information transfer characteristics in the time–frequency domain, screen closely related muscle pairs and perform directional coupling significance analysis. Palmaris longus (PL) played a dominant role under wrist flexion movements(WF), Extensor Carpi Radialis (ECR) played a dominant role under wrist extension movements(WE), and the remaining muscles responded to them with information and Biceps Brachii (BB) played a responsive role throughout the movement; flexor pairs had the highest positive coupling values in the beta band during Conversion action1 (MC1) and WF phases, and extensor pairs had the highest positive coupling values in the gamma band during Conversion action2(MC2) phase and the highest coupling values in the beta band during WE phase. TVPDC can effectively analyze the multichannel intermuscular directional coupling and information transmission relationship of surface electromyography under wrist flexion and extension transition movements, providing a reference for exploring the control mechanism of CNS and abnormal control mechanism in patients with motor dysfunction in a new perspective.

Simultaneous dual-channel data transmission through a multimode fiber via wavefront shaping

The increasing demand for transmission capacity in fiber-optic communications makes multimode fibers (MMFs) attractive by enabling simultaneous multi-channel data transmission. However, inherent mode crosstalk among transmission channels limits its applicability. In this Letter, we propose to overcome this problem via wavefront shaping. By actively modulating the incident light with a special wavefront, not only the transmitted power for a specific channel can be enhanced but also crosstalk among different transmission channels can be mitigated. As a proof of concept, we experimentally demonstrated wavefront shaping assisted dual-channel optical communications through a single MMF. 10 Gbaud four-level pulse amplitude modulation signals were sent through both channels simultaneously, enabling a total bit rate of 40 Gbps. Both channels were analyzed with bit error rates below the hard-decision forward error correction limit, confirming the validity of the proposed scheme.

Migration of elastic optical networks to the C + L-bands subject to a partial upgrade of the number of erbium-doped fiber amplifiers

Space division multiplexing (SDM) and band division multiplexing (BDM) are considered promising technologies to increase the capacity of optical transport networks. The progressive shortage of available dark fibers and the immaturity of multicore and multimode fibers for multichannel transmission induce network operators to postpone the process of capacity enhancement through SDM. Therefore, capacity increase revolves around BDM by lighting up at least the L-band of the already installed optical fiber infrastructure, which is a practical solution in the short to middle term. However, L-band activation requires the upgrade of network components such as erbium-doped fiber amplifiers (EDFAs). To manage the imposed cost while leveraging the L-band, a network can be partially rather than fully migrated in a single step by upgrading just a subset of the fibers and thus a subset of EDFAs to operate in the C+L-bands. In this paper, the focus is set on determining which fibers in the network should be upgraded to exploit the L-band, subject to a constraint on the maximum number of EDFAs to be upgraded, and analyzing its impact on network performance when facing dynamic traffic in terms of the blocking ratio. To this end, three heuristic algorithms, each pursuing a different objective, and two of them based on an integer linear programming (ILP) formulation, are proposed for the network planning to identify which fibers to upgrade. Simulation results demonstrate that, thanks to the use of these heuristics, the upgrade of a partial set of links to the C+L line system is a viable solution for network operators to circumvent the huge cost associated with migrating the full network. For instance, we demonstrate that a strategic partial upgrade using the proposed methods, subject to upgrading a maximum of 60% of the EDFAs, can significantly boost the supported traffic load in the examined topologies, ranging from 175% to 322%, when compared to the non-upgraded network.

Polarization-dependent multichannel transmission of 5G signals based on Zn0.91(Li0.5Bi0.5)0.09MoO4 low-temperature co-fired ceramics

Polarization-dependent multichannel transmission of 5G signals based on Zn0.91(Li0.5Bi0.5)0.09MoO4 low-temperature co-fired ceramics

10.51-Tbit/s multi-channel IF-over-fiber transmission with SDM/WDM/SCM for beyond-5G mobile fronthaul accommodating ultra-high-density antennas

In beyond-5G and 6G mobile communication systems, it is expected that massive numbers of antennas are densely deployed to provide a stable and high-speed communication environment. To efficiently accommodate high-density antennas, high-capacity mobile fronthaul (MFH) is also required. Intermediate-frequency-over-fiber (IFoF) is considered as one of the attractive solutions for realizing high-capacity MFH due to its high spectral efficiency and multi-channel transmission capability. In this paper, we demonstrate the highest-capacity IFoF transmission with combinations of space division multiplexing, wavelength division multiplexing, and subcarrier multiplexing; 4608 channels of 64-quadrature amplitude modulation orthogonal frequency division multiplexing signals with a total net bit rate of 10.51 Tbit/s (4608×380.16MHz/ch×6bit/s/Hz) are successfully transmitted over a 10.1-km uncoupled 12-core multi-core fiber.

Engineering Metal-Organic Frameworks with Tunable Colors for High-Performance Wireless Communication.

Metal-organic frameworks (MOFs) have emerged as excellent platforms possessing tunable and controllable optical behaviors that are essential in high-speed and multichannel data transmission in optical wireless communications (OWCs). Here, we demonstrate a novel approach to achieving a tunable wide modulation bandwidth and high net data rate by engineering a combination of organic linkers and metal clusters in MOFs. More specifically, two organic linkers of different emission colors, but equal molecular length and connectivity, are successfully coordinated by zirconium and hafnium oxy-hydroxy clusters to form the desired MOF structures. The precise change in the interactions between these different organic linkers and metal clusters enables control over fluorescence efficiency and excited state lifetime, leading to a tunable modulation bandwidth from 62.1 to 150.0 MHz and a net data rate from 303 to 363 Mb/s. The fabricated color converter MOFs display outstanding performance that competes, and in some instances surpasses, those of conventional materials commonly used in light converter devices. Moreover, these MOFs show high practicality in color-pure wavelength-division multiplexing (WDM), which significantly improved the data transmission link capacity and security by the contemporary combining of two different data signals in the same path. This work highlights the potential of engineered MOFs as a game-changer in OWCs, with significant implications for future high-speed and secure data transmission.

Analysis of the SpaceFibre technology for the high-bandwidth onboard networks

The paper presents an analysis of a prospective international standard SpaceFibre for on board data exchange for different types of aircraft. Paper provides the rationale for using of this standard for new generation on-board networks. The obtained results are based on many years of experience with the SpaceWire/SpaceFibre family of open international standards. The authors present the main problems of SpaceFibre, as well as ways to solve them. The first problem is related to the use of multi-channel data transmission in prospective Russian projects, as well as the need to increase throughput using existing equipment and physical cables. It is necessary to develop new transmission methods and algorithms and create a completely Russian version of the multilane level for the described standard. The second problem relates to the organization of data transmission in SpaceFibre networks with a large number of nodes and a complex scheme of data transfer flows, it is a consequence of an insufficiently developed network level of the standard. The authors give possible ways to solve the identified inconsistences of the standard using the concept of software-reconfigurable networks. The finalization of the SpaceFibre standard in terms of the discussed problems will improve the efficiency of the protocol itself, as well as take into account all possible comments before the stage of creating of a Russian State Standard for SpaceFibre.

IoT-based multi-channel information integration method for wireless sensor networks

The speedy progress of the Internet of Things has connected a huge network of smart devices in series and also intensified the pressure of multi-channel information transmission in wireless sensor networks. To solve the transmission of large amount of information, a multi-channel information integration method based on Radial Basis Function neural network, Particle Swarm Optimization algorithm and Dempster-Shafer evidence theory is studied. The method designs an improved counter propagation Radial Basis Function neural network prediction algorithm to correct the abnormal data based on the normal and abnormal values detected by the Grubbs criterion. And then it uses the Dempster-Shafer evidence inference method for information integration on the basis of the complete monitored values after correction obtained using the above method. The lab result indicated that mean absolute error value of the improved counter propagation Radial Basis Function model for anomaly data prediction findings was 4.399, mean square error was 26.820, and root mean squared error value was 5.180. The average time delay of information integration of this research method was 0.24 μs. Compared with other methods, this method has the shortest integration time delay and the highest integration accuracy. The study provides a new method in the multi-channel information integration for wireless sensor networks in the context of internet of things.

Study on the interaction between information dissemination and infectious disease dissemination under government prevention and management

In recent years, public health emergencies have occurred frequently around the world, and infectious diseases are one of the most destructive and influential events. The coupling effect between infectious disease transmission and information dissemination has been a research hotspot that scholars have focused on in recent years. Analyzing how to effectively prevent the impact of information dissemination on the process of infectious disease transmission from the perspective of government prevention and control has important theoretical significance. Firstly, this paper investigates the COVID-19 epidemic and establishes a coupled multi-channel network UFAT-SEIR transmission model under government prevention and management based on the characteristics of infectious disease transmission and information transmission. Considering the individual's ability to recognize information, the interaction between false information and real information, and the impact of group polarization, the step function is used to explore the results of the user's information decision-making process. Secondly, the microscopic Markov chain approach (MMCA) is constructed to derive the transmission threshold of infectious diseases related to the information transmission layer. Finally, simulation is performed based on the impact of government prevention and management actions on parameters. The research findings can provide relevant strategies and suggestions for the government to prevent and control the spread of infectious diseases.

Low crosstalk trapezoid-index thirteen-core single-mode fiber for multi-channel and high-density applications.

Multi-core fiber based on space division multiplexing technology provides a practical solution to achieve multi-channel and high-capacity signal transmission. However, long-distance and error-free transmission remains challenging due to the presence of inter-core crosstalk within the multi-core fiber. Here, we propose and prepare a novel trapezoid-index thirteen-core single-mode fiber to solve the problems that MCF has large inter-core crosstalk and the transmission capacity of single-mode fiber approaches the upper limit. The optical properties of thirteen-core single-mode fiber are measured and characterized by experimental setups. The inter-core crosstalk of the thirteen-core single-mode fiber is less than -62.50 dB/km at 1550 nm. At the same time, each core can transmit signals at a data rate of 10 Gb/s and achieve error-free signal transmission. The prepared optical fiber with a trapezoid-index core provides a new and feasible solution for reducing inter-core crosstalk, which can be loaded into current communication systems and applied in large data centers.

Joint WDM and OAM Mode Group Multiplexed Transmission Over Conventional Multimode Fiber

To exploit the advantages of multimode fiber (MMF)-based transmission and to improve the overall capacity, transmission of OAM modes over a single wavelength needs to be replaced by multichannel transmission with the proper experimental demonstration in terms of achievable bit error rates (BER), cross-talk(x-talk), etc. over the entire transmission band. In this paper, we have experimentally shown the successful transmission of two OAM mode groups multiplexed signals jointly with three channels using wavelength division multiplexing (WDM) over a 1 km conventional MMF, namely OM3. In this experimental study, each OAM mode over each WDM channel uses 10 Gbps of on-off keying (OOK) modulation format. At the receiver end, the achieved bit error rate (BER) is found well below the required pre-FEC BER of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$3.8\times 10^{-3}$</tex-math></inline-formula> without using any MIMO-DSP. To establish the efficacy of the signal transmission, the time evolutions of OAM mode x-talk and BER over wavelengths spanning the entire C-band have been experimentally measured. Under the influence of different x-talks, the BER performances of all three 50 GHz-spaced WDM channels for both OAM modes are measured. With proper adjustment of polarization at the receiver end, a BER value below the pre-FEC threshold is achieved over 900 seconds. The experimental results also revealed that the power penalty contribution of WDM x-talk is negligible compared to OAM mode x-talk.

Smart Insoles for Gait Analysis Based on Meshless Conductive Rubber Sensors and Neural Networks

In recent years, advances in wearable medical devices have been driven by the development of flexible sensors and wireless IoT technologies, with research and applications in this field rapidly increasing. Plantar pressure analysis is a gait method that can be used to analyze foot pressure during human movement to identify potential health problems, but most of the devices based on this method are currently single-functional, poorly portable, and expensive. This work proposes a smart insole using meshless conductive rubber sensors, as well as a multi-channel data acquisition and transmission system based on these sensors, deep learning networks, and Bluetooth technology. The smart insole sensing unit and circuit board were made of flexible materials and powered by rechargeable lithium batteries. The system can be used to collect plantar pressure data from the sensors in real time, analyze the pressure in different regions of the foot through a neural network, and infer the gait cycle and abnormal gait of the user. The effective communication range can be up to 70 meters under barrier-free conditions. This smart insole has a bright future thanks to the pressure detection range, fast response time, and good durability.

Multi-Channel Long-Distance Audio Transmission System Using Power-over-Fiber Technology

To establish stable communication networks in harsh environments where power supply is difficult, such as coal mines and underwater, we propose an effective scheme for co-transmission of analog audio signals and energy. By leveraging the advantages of optical fibers, such as corrosion resistance and strong resistance to electromagnetic interference, the scheme uses a 1550 nm laser beam as the carrier for analog audio signal propagation, which is then converted to electrical energy through a custom InGaAs/InP photovoltaic power converter (PPC) for energy supply and information transfer without an external power supply after a 25 km fiber transmission. In the experiment, with 160 mW of optical power injection, the scheme not only provides 4 mW of electrical power, but also transmits an analog signal with an acoustic overload point (AOP) of 105 dBSPL and a signal-to-noise ratio (SNR) of 50 dB. In addition, the system employs wavelength division multiplexing (WDM) technology to transform from single-channel to multi-channel communication on a single independent fiber, enabling the arraying of receiving terminals. The passive arrayed terminals make the multi-channel long-distance audio transmission system using power-over-fiber (PoF) technology a superior choice for establishing a stable communication network in harsh environments.

Development of Split Ring Resonator Shaped Six Element 2 × 3 Multiple Input Multiple Output Antenna for the C/X/Ku/K Band Applications

In this manuscript, we have numerically investigated and experimentally verified the six-element split ring resonator and circular patch-shaped multiple input, multiple output antenna operating in the 1–25 GHz band. MIMO antennas are analyzed in terms of several physical parameters, such as reflectance, gain, directivity, VSWR, and electric field distribution. The parameters of the MIMO antenna, for instance, the envelope correlation coefficient (ECC), channel capacity loss (CCL), the total active reflection coefficient (TARC), directivity gain (DG), and mean effective gain (MEG), are also investigated for identification of a suitable range of these parameters for multichannel transmission capacity. Ultrawideband operation at 10.83 GHz is possible for the theoretically designed and practically executed antenna with the return loss and gain values of −19 dB and −28 dBi, respectively. Overall, the antenna offers minimum return loss values of −32.74 dB for the operating band of 1.92 to 9.81 GHz with a bandwidth of 6.89 GHz. The antennas are also investigated in terms of a continuous ground patch and a scattered rectangular patch. The proposed results are highly applicable for the ultrawideband operating MIMO antenna application in satellite communication with C/X/Ku/K bands.

All-dielectric terahertz metasurface for linearly-polarized multichannel transmission and superposition states of spherical and vortex waves

Compared to pure vortex waves, the superposition state of spherical waves and vortex waves has enough degrees of freedom to upgrade applications in particle manipulation, information encryption, and large-capacity communications. Here, we propose a new scheme to achieve superposition states and multichannel transmission of vortex and spherical waves. Two transmissive all-silicon metasurfaces that enable mutual interference between linearly polarized (LP) waves in the terahertz region are demonstrated. Type A can achieve interference between x and y polarized waves, while type B can achieve interference between x (or y) and x (or y) polarized waves. The multichannel transmission and superposition states of topological charges of +3, +2, and +4 are designed and demonstrated from theoretical, simulative, and experimental perspectives at 1.1 THz. In addition, the objective fact that the focused superposition state must be observed close to the focal plane is also revealed. The measured results are in good agreement with the theoretical and simulative results. This work provides an idea for the design of ultrathin terahertz devices and could be applied in the fields of information encryption and high-frequency communications.

Meta-Learning Assisted Source Domain Optimization for Transfer Learning Based Optical Fiber Nonlinear Equalization

Transfer learning (TL) has been demonstrated its feasibility on fast remodeling for fiber nonlinearity equalization. It will be very efficient with fine-tuning rather than retraining when the channel parameters have been changed, e.g., the optical launch power and fiber distance. However, the performance is dependent on the highly correlation between the source and target tasks. An improper source domain cannot improve the efficiency or even negative transfer. In this paper, we propose a meta-learning assisted source domain optimization scheme in single- and multi-channel transmissions. We construct the support dataset and query dataset from the information of the inner-task and the across-task to train the neural network so that we can find a unified source domain and efficiently adapt to different tasks with fewer epochs. We conduct an experiment to transmit 120-Gb/s dual polarization (DP) 16-QAM signal over 800-km standard single mode fiber (SSMF). The required epochs for convergence can be significantly reduced and there is slight Q-factor improvement with meta-learning algorithm compared with retraining and conventional TL. We also analyze the TL strategy in multi-channel system. The simulation results show that meta-learning can also help to optimize the source domain with lower complexity.