High-speed Transmission Research Articles

Performance enhancement of high-speed free space optical transmission link for the implementation of 5G and internet of things

Performance enhancement of high-speed free space optical transmission link for the implementation of 5G and internet of things

High-Speed and Low-Noise Gear Finishing by Gear Grinding and Honing: A Review

AbstractGears are important mechanical parts for transmitting power and play an increasingly important role in the machinery industry. The electric vehicle industry developed rapidly and became a vital development field of the automotive industry over the past few years. The conversion of energy increases the requirements for electric vehicle transmissions, which promotes the development of high-speed and low-noise transmission gear. This paper elaborates on the research progress of high-speed and low-noise gear finishing methods. Firstly, this review analyses the machining requirements, finishing, and specific machining technologies of high-speed and low-noise gears. The importance of gear grinding and honing in high-speed and low-noise gear machining is highlighted. Secondly, the applications of gear grinding and honing in gear modification, error compensation, and texture control are analyzed. Furthermore, the role of precision machining technology in improving gear performance is clarified. Finally, the design and processing methods of the modified tooth flank for gear modification are summarized. In addition, the influence of tooth surface texture on noise is described, and the texture change methods are explored. The well-known open problems of gear finishing are finally identified, and some new research interests are also pointed out. This review will provide valuable references for further research on gear finishing.

Double-pole anti-dark solitons for a Lakshmanan-Porsezian-Daniel equation in an optical fiber or a ferromagnetic spin chain

Under investigated in this paper is a Lakshmanan-Porsezian-Daniel equation that describes the nonlinear spin excitations in a (1+1)-dimensional isotropic biquadratic Heisenberg ferromagnetic spin chain with the octupole-dipole interaction or the propagation of the ultrashort pulses in a long-distance and high-speed optical fiber transmission system. Under certain parameter conditions, we simultaneously take the multi-pole phenomena and breather-to-soliton transitions into account, then utilize the second-order generalized Darboux transformation to derive the double-pole anti-dark solitons and graphically illustrate them. Asymptotic analysis is conducted to examine the interaction properties of double-pole anti-dark solitons, including their characteristic lines, amplitudes, phase shifts, slopes and position differences. Unlike the double-pole anti-dark solitons found in the Hirota equation, the ones in this study exhibit a distinct feature: Different soliton components share the same amplitude.

Plasmonic antennas based on rectangular graphene nanoribbons with controlled polarization of terahertz and infrared radiation

Background. To develop new terahertz wireless communication systems with high throughput and transmission speeds, such as 6G and above, effective control of the polarization direction of emitted terahertz waves is necessary, but most methods are technologically complex and expensive. The implementation of terahertz antennas and devices based on 2D materials such as graphene solves the problem associated with developing effective control. Aim. Study of the possibility of controlling the polarization of terahertz and IR radiation of plasmonic antennas based on rectangular graphene nanoribbons by changing the chemical potential (application of an external electric field). Methods. This important scientific problem related to the design of terahertz antennas can largely be solved by simulation using the electrodynamic simulation program CST MWS 2023. Results. Plasmon terahertz antennas based on rectangular graphene nanoribbons were chosen as the object of analysis and the possibility of emitting waves of two orthogonal polarizations was shown. Methods have been identified for controlling the polarization of terahertz and IR radiation from such antennas, based on the selection of operating frequencies corresponding to the resonances of the modes of surface plasmon-polaritons, and the application of metallization to the dielectric substrate. Conclusion. The ability to control the polarization of terahertz and IR radiation makes it possible to create both new elements of plasmonic antenna arrays and new communication technologies, including future 6G networks.

Full van der Waals Ambipolar Ferroelectric Configurable Optical Hetero-Synapses for In-Sensor Computing.

The rapid development of visual neuromorphic hardware can be attributed to their ability to capture, store and process optical signals from the environment. The main limitation of existing visual neuromorphic hardware is that the realization of complex functions is premised on the increase of manufacturing cost, hardware volume and energy consumption. In this study, we demonstrated an optical synaptic device based on a three-terminal van der Waals (vdW) heterojunction that can realize the sensing functions of light wavelength and intensity as well as short-term and long-term synaptic plasticity. In the image recognition task, we constructed an optical reservoir neural network (ORNN) and a visible light communication system (VLC) composed of this optical synaptic device. The ORNN has a recognition rate of up to 84.9% for 50 000 color images in 10 categories in the CIFAR-10 color image dataset, and the VLC system can achieve high-speed transmission with an ultra-low power consumption of only 0.4 nW. This work shows that through reasonable design, vdW heterojunction structures have great application potential in low-power multifunctional fusion application tasks such as visual bionics.

RGB-Single-Chip OLEDs for High-Speed Visible-Light Communication by Wavelength-Division Multiplexing.

Organic light-emitting diodes (OLEDs) have been developed for high-speed transmitters of visible-light communication (VLC) but so far the possibility of direct fabrication of multiple colors on a single substrate has not been exploited for multi-Gbps data transmission. Very fast red-, green-, and blue (RGB)-emitting OLEDs are developed on a single substrate to realize high data transmission speed by wavelength division multiplexing (WDM). -6dB electrical bandwidth of over 100MHz is achieved for all colors by selecting fluorescent materials with nanosecond emission lifetimes and little overlap between their emission spectra and incorporating them into OLEDs designed for high-speed operation. Optical microcavities in top-emitting OLED structures are used to minimize spectral overlap. A record data transmission rate for an OLED transmitter system of 3.2Gbps is demonstrated, by transmitting data with the 3 colors simultaneously and separating each data by dichroic mirrors. The results show that WDM with integrated RGB pixels is a useful way to increase the data transmission rate of a VLC system based on OLED transmitters, which has the potential to enable multi-gigabit transmission by displays. The availability of high-speed multiple-color devices as developed here also expands applications of OLEDs for spectroscopy, sensing, and ranging.

Lubrication optimization of high-speed train drive gearbox

The gears in the high-speed heavy-duty gearbox of the high-speed train are typical high-speed heavy-duty gears. Combined with the transmission principle and structural characteristics of the high-speed train drive gearbox, to ensure adequate lubrication of meshing gears and bearings, an optimization of the lubricating oil flow inside the gearbox was conducted. The oil and gas two-phase flow model inside the gearbox adopts the VOF model, and the turbulence model adopts the standard κ-ε model. Fluent is used for simulation calculation. The results show that the exhaust port position of the gearbox has little effect on the flow of lubricating oil inside the gearbox; the overall pressure distribution inside the gearbox is relatively uniform, with higher pressure only at the meshing gears; the distribution of lubricating oil inside the gearbox is related to the rotation of the gears, and the flow velocity of lubricating oil is mainly affected by the rotation of the gears, with the maximum flow velocity appearing around the gears; the flow of lubricating oil inside the gearbox meets the lubrication requirements of the gearbox. These results provide support for the lubrication design, flow channel structure improvement, and effectiveness evaluation of high-speed train transmission gearboxes.

Wedge-loading planetary traction drive: Modeling and performance analysis

The continuous development of motors with high speed and high power density has significantly increased the demand for high-speed reducers. Traction drive has emerged as a new option for high-speed reducers due to its high transmission efficiency and accuracy in high-speed transmission. In the previous theoretical studies on traction drive, the traction coefficient was set as a fixed value, and the influence of elastohydrodynamic lubrication (EHL) on the traction coefficient was ignored. Therefore, this paper investigated the wedge-loading planetary traction drive (WL-PTD) and established a theoretical model combining the macroscopic and microscopic traction mechanisms of the traction drive based on Hertzian contact and mixed elastohydrodynamic lubrication (mixed EHL). The loading principle and transmission performance of WL-PTD were studied through numerical computations, and the effects of different design parameters on transmission performance were discussed. When the input speed of WL-PTD was 10,000 rpm, the peak value of the global sliding coefficient was approximately 1.27×10−5, and the maximum transmission efficiency reached 97.41%, indicating an excellent transmission performance of the WL-PTD. The findings of this study can provide theoretical guidance for subsequent optimization design.

An efficient non-binary QC-LDPC coded modulation scheme for long-haul optical systems

Abstract Coded modulation (CM), which combines channel codes with high-dimensional modulation schemes, is an attractive technique to improve the spectral efficiency in high-speed optical transmission systems. Non-binary low-density parity check (NB LDPC) codes can provide larger coding gains with smaller codeword lengths compared to their binary counterpart, in addition to reducing the latency of the system. The majority of works based on NB LDPC CM focus on bit-interleaved CM (BICM) and the widely used additive white Gaussian noise (AWGN) channel model. However, the Gaussian channel model is not a realistic model for long-haul intensity-modulated direct-detection (IM/DD) optical systems using erbium-doped fiber amplifiers. In this paper, it is mathematically proved that noise in the received signals after photodetection can be more accurately represented using chi-squared distribution. The efficiency of CM depends on the mapping between coded symbols and the constellation signal points of the modulation scheme. Hence, a symbol interleaved CM with subcarrier modulation for NB LDPC codes based on the proposed channel model is presented in this paper to improve the bit-error rate (BER) performance. The simulation results show that the proposed CM for NB LDPC codes with M-ary quadrature amplitude modulation schemes provides better performance than BICM. The analysis of the error performance of the proposed system gives a coding gain of 1 dB at a BER of 10−7 compared to that of the AWGN channel model. The performance improvement of the system is also evaluated in terms of spectral efficiency and link distance.

A wideband dual-circularly polarized traveling wave dielectric resonator antenna array

ABSTRACT In order to meet the demand of high capacity and high speed transmission of satellite communication system, a wideband dual-circularly polarized dielectric resonator antenna (DRA) array is proposed based on the traveling wave principle. Four DRA elements with slot-coupling excitation are sequentially placed on the ground, and the feeding network is designed to realize the two orthogonal circular polarization radiation waves. A notched copper loop (NCL) around the antenna array is adopted to improve the radiation performance. Depending on the operation of the two ports, the NCL generates the induced currents which rotates clockwise/counterclockwise, increasing the axial ratio bandwidth. In order to further improve the gain stability, the copper sheets are embedded on the top surface of each radiation element, and the copper cylinders perturb the internal field distribution of the DRA to introduce higher-order modes. The measurement results show that the left-hand circular polarization and the right-hand circular polarization operating bandwidths are 11.8% (14.97–16.85 GHz) and 12% (14.91–16.82 GHz). The antenna gain achieves 9.0 dBic. This DRA array can be applied for the vehicle mounted RF terminals in satellite communication.

Design of a triggerless readout electronics system for CDEX-50

Direct detection of light-mass dark matter is a frontier topic in international physics research. The reduction of system threshold is important in order to improve the sensitivity of light-mass dark matter detection. The scientific goal of the China Dark Matter Experiment (CDEX) at Jinping Underground Laboratory in China is to detect WIMPs utilizing a high-purity germanium array detector. CDEX-10 achieved the most sensitive results in the 4 to 5 GeV/c 2 range. CDEX-50 aims to achieve an energy threshold of 100 eV, which significantly increases data bandwidth and complicates the implementation of noise reduction algorithms, thereby posing challenges to the readout electronics system. In this paper, a triggerless readout electronics system based on FPGA-GPU is designed for CDEX-50, which can achieve full energy range detection from 100 eV to 10 MeV. A verification prototype of a triggerless electronics system utilizing a Broad Energy Germanium (BEGe) detector has been developed to test the performance of high-bandwidth transmission and data processing. The results demonstrate that the bit error rate for the high-speed transmission link of the triggerless readout electronics system is below 1015. Furthermore, the FPGA-GPU transmission bandwidth, utilizing P2P DMA, achieves 100.2 Gbps, and the mean filter implemented on the GPU is capable of processing a 64 Gbps data stream in real-time. These results provide foundation for the design of the triggerless readout electronics system for CDEX-50.

Augmented Reality and Virtual Reality: A New Way of Seeing the World

Technologies such as (AR) Augmented Reality &(VR) Virtual Reality, which provide immersive digital experiences, interactive environments, simulation, and engagement, have completely changed how we approach learning. However, in order to meet the huge demand in education, these technologies which are still in the emerging stage need to be heavily customized and heavily invested in. This thorough analysis seeks to contextualize the last few years of development of Virtual and Augmented Reality in the Education. For additional study, a total one thousand five hundred and thirty-six articles are chosen using text mining and theme analysis techniques. Based on earlier research on AR and VR in education, hypotheses were developed and are currently being processed and analysed to reveal the current development in literature via Augmented Reality and Virtual Reality, applications, benefits, and future directions. The findings show that wearable technology has contributed significantly to the exponential expansion in the use of Virtual and Augmented Reality in education in recent years. Results also highlight the need for faster adoption and customization of these technologies in educational institutions, based on secondary data. An increasing number of educational applications for the learning process are emerging as Virtual and Augmented Realityexp and quickly. It is advised that researchers stay up to date on the gaps in AR and VR’s Changeover to education &develop practical adaptation strategies to maximize the benefits of these technological development with significant developments in high-speed transmission and processing, AR &VR are developing as Display Platforms for Next Generation for more intimate human-digital interactions. Nonetheless, matching the extraordinary Human Vision Performance while keeping Near the Eye Display module tiny and lightweight presents unprecedented hurdles for optical engineering. Fortunately, new advances in Holographic Optical Elements HOEs and Lithography Enable Devices present novel approaches to overcoming these challenges in Virtual and Augmented Reality which would otherwise be problematic with traditional optics

Bias-aided DD-LMS equalizer for optical multipath-interference-impaired high-speed PAM4 transmission systems

Multipath interference (MPI) noise induces drastic fluctuations in high-speed 4-level pulse amplitude modulation (PAM4) intensity modulation direct detection (IMDD) systems, severely degrading the transmission performance. Here, we propose a bias-aided decision-directed least mean square (DD-LMS) equalizer to eliminate the MPI noise. In the simulation, the proposed bias-aided DD-LMS equalizer could adeptly track and compensate the MPI-impaired PAM4 signal, markedly improving the bit error rate (BER) performance under different MPI levels and laser linewidths. Within a 112 Gbps PAM4 transmission system, the proposed equalizer achieves a MPI tolerance over 4 dB at the KP4-forward error correction (FEC) threshold (2.4 × 10−4), outperforming existing MPI suppression techniques.

Analyze the impact of nonlinear distortions on OFDM-based visible light communication systems

Visible light communication (VLC) has gained attraction for its use in high-speed wireless connectivity leveraging LED lighting elements. Orthogonal Frequency Division Multiplexing (OFDM) is an attractive modulation scheme due to its spectral efficiency and resilience to multipath distortion. However, the nonlinear electro-optic transfer characteristics of optical components introduce signal clipping and quantization noise which corrupt OFDM signals. This paper provides an in-depth analysis of clipping and quantization noise to quantify the impact of LED nonlinearities on OFDM-based VLC system performance. Detailed mathematical models are derived for clipping distortions caused by LED optical power saturation and quantization errors from ADC/DAC finite precision in the modulator and driver circuitry. This analysis is quantified through simulations of the degradations in terms of error vector magnitude (EVM), signal-to-noise ratio (SNR) loss, and bit error rate (BER) under varying clipping ratios and quantization bit-depths. The 16-QAM OFDM transmission shows that the LED driver should possess at least 12 dB signal linear dynamic range and 3-bit quantization to restrict SNR penalty within 3 dB. Adaptive tone mapping and digital pre-distortion techniques are examined to compensate for intensity distortions enabling high-speed OFDM transmission over VLC links.

Analyzing Performance of THz Band Graphene-Based MIMO Antenna for 6G Applications

In this paper, a compact 2×2 hexagon ring-shaped MIMO antenna operating at the terahertz band is proposed for future 6G wireless communication applications. The antenna is designed using graphene, due to its unique high-speed transmission capabilities. DGS and NL decoupling approaches are applied to enhance isolation between the two radiating elements. A parametric study is performed to investigate the significance of using these methods. Performance in terms of different metrics is studied using the CST Microwave Studio simulator. The final outcomes show that the proposed MIMO antenna achieves 23 dB of isolation, 0.004859 of ECC, 0.004 bits/sec/Hz of CCL, and efficiency of 98%.

Ultra-Wideband Common-Mode Rejection Structure with Autonomous Phase Balancing for Ultra-High-Speed Digital Transmission.

For ultra-high-speed digital transmission, required by 5G/6G communications, ultra-wideband common-mode rejection (CMR) structures with autonomous phase-balancing capability are proposed. Common-mode noise, caused by phase and amplitude unbalances, is one of the most undesired disturbances affecting modern digital circuits. According to the circuit design guides with a typically used differential line (DL) for high-speed digital transmission, common-mode rejection is achieved using CMR filters, and the unbalanced phase, caused by a length difference between the two signal lines of a DL, is compensated by inserting an additional delay line. However, due to nonlinear phase interactions between the two DLs and unbalanced electromagnetic (EM) interferences, the conventional compensation method is frequency-limited at around 10 GHz. To significantly enhance the common-mode rejection level and extend the phase recovery bandwidth, the proposed CMR structure utilizes a planar balanced line (BL), such as a coplanar stripline (CPS) or a parallel stripline (PSL), along with additional conductor strips arranged laterally near the BL. To demonstrate the performance of the proposed BL-based CMR structures, various types of CMR structures are fabricated, and the measurement results are compared with the 3D EM simulation results. As a result, it is proven that the proposed BL-based CMR structures have the capability to reject the common-mode noise with suppression levels of more than 10 dB and to simultaneously recover the phase balance from near DC to over 40 GHz.

Spectrally efficient DWDM system using DQPSK modulation

Abstract DWDM technology is gaining popularity in fiber-optic communication due to high-speed transmission channel capacity demands. The adoption of this system has been driven by this demand. Researchers focus on optimizing data transmission parameters within channel characteristics for maximum performance. The signal’s form typically influences the optical channel capacity, the guiding medium’s dispersive and non-linear characteristics, and interference from multiple sources. This study investigates how efficient modulated systems control linear and non-linear impairments in optical channel capacity due to high data rates transmitted over optical communication networks, aiming to circumvent current issues. The selection of pulse shape and modulation format is crucial for an effective DWDM optical communication system due to the rigorous specifications of the optical channel. Modulation formats like intensity and phase have become viable network design technologies, allowing for network creation that operates to the designer’s satisfaction. This academic study examines the theoretical properties of various models used to analyze and recreate high-speed optical communication links, aiming to understand the impact of system components and modulation techniques.

A novel method of high-speed all-optical logic gate based on metalens

This paper introduces a novel approach to constructing all-optical logic gates based on metalens. The designed structure enables the realization of five commonly used logic gates (AND, OR, NOT, XOR, XNOR). Each logic gate is composed of two to three metalenses. The advantages of this approach are as follows: 1. Metalens offer flexible phase control capabilities, overcoming the strict phase requirements in traditional optical logic gate design. 2. The miniaturization of the metalens makes integration possible and provides a potential method for high-speed parallel optical computing. 3. By controlling different types and quantities of metalens, various types of logic gates can be formed, enhancing programmability during use. The contrast values for the designed logic gates are as follows: 27.95 dB (OR), 18.18 dB (AND), 10.83 dB (NOT), 10.29 dB (XNOR), and 13.56 dB (XOR). With similar structures, the bit rates for the five logic gates at a 50% duty cycle range from 1.04 to 1.05 Tb/s. Overall, these results demonstrate a successful balance between contrast and transmission speed when utilizing metalens to realize all-optical logic gates. From the results, the logic gate proposed in this paper has high contrast and transmission speed, which proves the rationality of using metalens to realize all-optical logic gate.

Unipolar quantum optoelectronics for high speed direct modulation and transmission in 8–14 µm atmospheric window

The large mid-infrared (MIR) spectral region, ranging from 2.5 µm to 25 µm, has remained under-exploited in the electromagnetic spectrum, primarily due to the absence of viable transceiver technologies. Notably, the 8–14 µm long-wave infrared (LWIR) atmospheric transmission window is particularly suitable for free-space optical (FSO) communication, owing to its combination of low atmospheric propagation loss and relatively high resilience to turbulence and other atmospheric disturbances. Here, we demonstrate a direct modulation and direct detection LWIR FSO communication system at 9.1 µm wavelength based on unipolar quantum optoelectronic devices with a unprecedented net bitrate exceeding 55 Gbit s−1. A directly modulated distributed feedback quantum cascade laser (DFB-QCL) with high modulation efficiency and improved RF-design was used as a transmitter while two high speed detectors utilizing meta-materials to enhance their responsivity are employed as receivers; a quantum cascade detector (QCD) and a quantum-well infrared photodetector (QWIP). We investigate system tradeoffs and constraints, and indicate pathways forward for this technology beyond 100 Gbit s−1 communication.

The condition monitoring scheme for industrial IoT scenario: A distributed modeling for high-dimensional nonstationary data

Based on large-scale data collection and high-speed transmission, Industrial Internet of Things (IIoT) promotes the rapid development of intelligent manufacturing. IIoT systems are usually disturbed by complex external factors, which lead to high-dimensional nonstationary operating data. Besides, unexpected data transmission interruptions, sensor failures, and network delays lead to data loss. This paper proposes a distribution & communication strategy for monitoring high-dimensional nonstationary processes with missing values in IIoT scenarios. First, a deep learning-based imputation network is proposed to impute the missing values. Then a decomposition strategy based on degree of cointegration is proposed, which decomposes a high-dimensional nonstationary process into multiple blocks. And a communication strategy is proposed to mine the internal relationship between different blocks. Finally, faulty information is detected by a distributed framework. Two real cases from IIoT are applied to illustrate the monitoring performance of the proposed method. The results show that the proposed method outperforms existing benchmarks in data imputation and monitoring performance.