Line Rate Research Articles

The Identification of Broomcorn Millet bZIP Transcription Factors, Which Regulate Growth and Development to Enhance Stress Tolerance and Seed Germination.

Broomcorn millet (Panicum miliaceum L.) is a water-efficient and highly salt-tolerant plant. In this study, the salt tolerance of 17 local species of broomcorn millet was evaluated through testing based on the analysis of the whitening time and the germination rate of their seeds. Transcriptome sequencing revealed that PmbZIP131, PmbZIP125, PmbZIP33, PmABI5, PmbZIP118, and PmbZIP97 are involved in seed germination under salt stress. Seedling stage expression analysis indicates that PmABI5 expression was induced by treatments of high salt (200 mM NaCl), drought (20% W/V PEG6000), and low temperature (4 °C) in seedlings of the salt-tolerant variety Y9. The overexpression of PmABI5 significantly increases the germination rate and root traits of Arabidopsis thaliana transgenic lines, with root growth and grain traits significantly enhanced compared to the wild type (Nipponbare). BiFC showed that PmABI5 undergoes homologous dimerization in addition to forming a heterodimer with either PmbZIP33 or PmbZIP131. Further yeast one-hybrid experiments showed that PmABI5 and PmbZIP131 regulate the expression of PmNAC1 by binding to the G-box in the promoter. These results indicate that PmABI5 can directly regulate seed germination and seedling growth and indirectly improve the salt tolerance of plants by regulating the expression of the PmNAC1 gene through the formation of heterodimers with PmbZIP131.

Anticancer effects of zapotin flavone in human gastric carcinoma cells are mediated via targeting m-TOR/PI3K/AKT signalling pathway.

The current study aims to investigate the anticancer effects of zapotin flavone in human gastric carcinoma cells. MTT assay was performed to determine the cytotoxicity effects of zapotin against the gastric cancer cells (SNU-1) and normal gastric cells (GES-1). SNU-1 cell morphology was analyzed through phase-contrast microscopy. Apoptosis was identified through DAPI staining assay and quantified through annexin V/propidium iodide (PI) staining. The effects on cell migration and invasion were carried out through transwell assay. Apoptosis and m-TOR/PI3K/AKT signalling pathway related proteins were analysed through western blotting. Proliferation rate of gastric cancer SNU-1 cell line declined with enhanced zapotin concentrations in comparison to normal GES-1 cells. Substantial morphological changes after zapotin exposure, including nuclear condensation and membrane rupture was observed. Further, increasing number of apoptotic cells, suppression of both cell migration and invasion was observed with increased zapotin concentrations. Finally, western blotting indicated significant blocking of m-TOR/PI3K/AKT signalling pathway. We conclude that zapotin can act as a potential drug against the gastric cancer.

Nonlinearity-aware PS-PAM-16 transmission for C-band net-300-Gbit/s/λ short-reach optical interconnects with a single DAC.

A nonlinearity-aware signal transmission scheme based on a low-complexity 3rd-order diagonally pruned absolute-term nonlinear equalizer (NLE) with weight sharing (DP-AT-NLE-WS) and rate-adaptable probabilistically shaped 16-level pulse amplitude modulation (PS-PAM-16) signal is proposed and experimentally demonstrated for C-band net-300-Gbit/s/λ short-reach optical interconnects. By replacing the multiplication operation with the absolute operation and applying weight sharing to reduce the kernel redundancy, the computational complexity of the proposed 3rd-order DP-AT-NLE-WS is reduced by >40% compared with the 3rd-order DP-Volterra NLE (DP-VNLE), DP-AT-NLE, and DP-VNLE-WS, with the achieved normalized general mutual information (NGMI) above a threshold of 0.857. Employing a commercial 32-GHz Mach-Zehnder modulator (MZM) and a single digital-to-analog converter (DAC), we demonstrate the single-lane transmission of 100-GBaud PS-PAM-16 signal using DP-AT-NLE-WS in the C band at record 370-Gbit/s line rate and 300.4-Gbit/s net rate over 1-km standard single-mode fiber (SSMF), achieving 21.2% (15.5%) capacity improvement over 100 (105)-GBaud PAM-8 transmission. To the best of our knowledge, this is the first net-300-Gbit/s intensity modulation and direct detection (IM/DD) short-reach transmission in the C band using commercially available components.

Investigating the Effect of the Interaction of Maize Inducer and Donor Backgrounds on Haploid Induction Rates.

Doubled haploid technology is a feasible, fast, and cost-efficient way of producing completely homozygous lines in maize. Many factors contribute to the success of this system including the haploid induction rate (HIR) of inducer lines, the inducibility of donor background, and environmental conditions. Sixteen inducer lines were tested on eight different genetic backgrounds of five categories in different environments for the HIR to determine possible interaction specificity. The HIR was assessed using the R1-nj phenotype and corrected using the red root marker or using a gold-standard test that uses plant traits. RWS and Mo-17-derived inducers showed higher average induction rates and the commercial dent hybrid background showed higher inducibility. In contrast, sweet corn and flint backgrounds had a relatively lower inducibility, while non-stiff stalk and stiff stalk backgrounds showed intermediate inducibility. For the poor-performing donors (sweet corn and flint), there was no difference in the HIR among the inducers. Anthocyanin inhibitor genes in such donors were assumed to have increased the misclassification rate in the F1 fraction and, hence, result in a lower HIR.

Advanced prevention against icing on high voltage power lines

Historical meteorological data indicates, that our weather is becoming more and more extreme. For the electrical utility operators (Distribution System Operators - DSOs and Transmission System Operators - TSOs), these changes arise in new operation challenges that need to be addressed. For example, frequent icing phenomenon affects all the components of the power line by a significant mechanical overload: it endangers the conductors, the insulators and the towers, as well. The result is often fatal and beside serious failures, it effects on operators’ decisions. These not only endanger the reliability of electrical grids by the loss of a power line for weeks or even months, but in general, the safety in the surroundings of the power line. As technology advances, we will be able to collected, analyses and predict very large databases in the field of meteorology and electrical engineering. The ability of processing mentioned data, combined with know-how results in the capacity to operate power lines at their thermal limits during different ambient parameters. This technology called Dynamic Line Rating (DLR) – is not only a great way to increase the transmission capacity of a given line, but can also be effectively used to prevent, or even solve icing-related issues. Higher currents result in higher Joule-heats, that consequently heat the conductors. If limits can be reached or approached, icing can be prevented. If prevention is not possible, detection and removal of ice layer is necessary. The proper handling of this icing issues, requires advanced algorithms (expert systems) and reliable measuring equipment. The combination and synchronization between algorithms, weather service and measuring equipment is the key of the successful operation. An EU H2020 financed project called FLEXITRANSTORE has just been launched to develop a cross-country co-operation, with objective to improve anti-icing and de-icing solutions. To establish and analyse different solutions, the project includes several universities, TSOs and DSOs. To solve mentioned icing issues Budapest University of Technology and Economics’ (BME) developed an advanced neural-network based algorithm which use OTLM system. It is planned to install and demonstrate the capabilities of this new technology on the DSOs grid (Electro Ljubljana - ELJ). Besides the introduction of DLR and icing, this paper also focuses on the preparation/organisation of co-operation between different companies and universities.

CLB: Coarse-Grained Precision Traffic-Aware Weighted Cost Multipath Load Balancing on PISA

This paper presents CLB, a programmable switch-based general-purpose in-network load balancer that can adapt to traffic changes at a very high speed. It uses Weighted-Cost Multipath (WCMP) mechanism for traffic-aware load balancing over many paths at a coarse-grained precision. CLB can be configured to match the load balancing requirements of a wide range of applications at line rate. We have analytically shown that CLB can achieve a bounded response time to traffic changes in the data plane. We implement CLB using the P4 programming language. Our experimental evaluation shows CLB can successfully distribute the incoming load over multiple paths for a given path-weight distribution and leads to performance improvement compared to other load balancing schemes.

Hermes — a robust, low latency, optical link protocol for synchronous data transfer at commercial asynchronous line rates

The CMS Level-1 Trigger at HL-LHC and associated upstream systems employ more than 10000 25 Gb/s optical links, transferring almost a Pb/s of data synchronously between the different back-end processing nodes. Stable operation of these links is essential to avoid the injection of erroneous signals into the trigger path, potentially leading to a flood of false triggers or data loss. The Hermes protocol, implemented on Xilinx UltraScale+ FPGAs, provides this stability while operating at asynchronous, industry standard line rates. The protocol design as well as results on the performance from extensive testing are presented here.

Lightning Performance of Unshielded 220 kV Transmission Lines Equipped With Metal Oxide Arresters

Overhead ground wires installed on transmission lines have been proved to be effective to protect conductors from direct lightning strokes, but ground wire breakouts due to icing are frequently reported. In order to prevent electric failure accidents caused by ground wire breakouts under icing conditions, unshielded transmission lines equipped with metal oxide arresters (MOAs) whole line have been proposed in high mountainous areas. Compared with ordinary transmission lines, lightning stroke risk of unshielded lines is much higher. In order to improve the lightning performance of unshielded lines, it is necessary to obtain the essential lightning energy absorption ability of the MOAs installed on unshielded lines. In this article, simulation model of unshielded 220 kV transmission lines equipped with MOAs is built, the influences of lightning parameters, striking occurrence point and grounding resistance on the absorbed energy of MOAs are analyzed. Based on Monte Carlo method, lightning trip-out rate of unshielded transmission lines are calculated, and suggested energy absorption ability of MOAs is proposed, which can give references for the improvement of power supply reliability of transmission lines.

Comprehensive Assessment of Lightning Protection Schemes for 10 kV Overhead Distribution Lines

This paper presents an assessment of lightning protection schemes for overhead lines from two aspects: protection performance and economic cost. Considering the random nature of lightning, the Monte-Carlo method with a heuristic technique is applied in the assessment. The one-dimensional finite-difference time-domain method is adopted to evaluate lightning overvoltages on insulators and lightning currents in surge arresters for failure assessment. The failure rate of an overhead line is addressed under both direct lightning and indirect lightning. A reduced set of design parameters are identified. It is found that the line insulation itself with a critical flashover overvoltage of less than 200 kV is not sufficient for lightning protection, especially against direct strokes. With other protection options, however, increasing the insulation level can greatly improve the protection performance. Installing surge arresters on every pole results in the best protection performance, but could be extremely expensive due to the replacement of failed surge arresters. The shielding wire provides moderate protection performance with a relatively low cost. The combination of the shielding wire and surge arresters provides much better performance under a wide range of soil conductivity with a moderate cost. It is worth mentioning that adopting high insulation strength for overhead lines in the new-line design could lead to significant cost savings for lightning protection. Guidelines for selecting design parameter values and protection schemes are provided, as well as a procedure for performance-cost evaluation.

High-Speed Terahertz Band Radio-Over-Fiber System Using Hybrid Time-Frequency Domain Equalization

The radio-over-fiber (RoF) orthogonal frequency division multiplexing (OFDM) system at Terahertz (THz) band has been a promising solution to meet the demand for high capacity and flexibility. The signals transmitted in the RoF system will suffer severe impairments caused by the wireless multi-path effect, optical fiber transmission, and photoelectric device response. The time-frequency domain equalization (TFDE) based on the two-dimension convolution (Conv2D) neural network (NN) is proposed to resist the linear and nonlinear impairments of the RoF-OFDM system. Furthermore, complex convolution is applied to compensate for the complex channel response. Compared with several baseline models, the detailed performance improvement and model size discussion of the complex-valued Conv2D NN TFDE are investigated. With the aid of the complex-valued Conv2D NN TFDE, the 16 Gbaud 16-ary quadrature amplitude modulation (16QAM) signals are delivered over 54.6 m wireless distance and 20 km standard single mode fiber. The line rate of this RoF system achieves 53.5 Gbit/s.

An ultra-thin silicon nitride membrane for label-free CTCs isolation from whole blood with low WBC residue

Microfiltration is the most straightforward and effective method to enrich circulating tumor cells (CTCs) from large numbers of background blood cells in the peripheral blood. It is still very challenging to achieve both high recovery of CTCs and low residue of white blood cells (WBCs) through one-time whole blood filtration. In this study, through a simulation, we revealed that reducing the thickness of the filter significantly reduces the WBC residue. A filter device was created using a 400-nm-thick Si3N4 membrane. The recovery rates of A549 and MCF-7 tumor cell lines were 82.04 ± 1.19% and 86.53 ± 3.27%, respectively, while the residual number of WBCs was largely reduced from 6.84 × 106 cells/mL cells to 604 ± 33.74 cells/mL. In addition, the assembled device could process whole blood without pretreatment at a high throughput of 1 mL/min. Utilizing as small volume of peripheral blood as 1 mL, CTCs were enriched by our device in four of six lung cancer patients and four of five breast cancer patients. The lower WBC residue is advantageous in CTC enumeration and subsequent proteomic or genomic characterization. Therefore, this technology enables label-free CTC isolation with a low WBC residue from whole blood, paving the way for a CTC analysis in clinical applications.

Typical wheel–rail profile change rules and matching characteristics of high speed railway in China

PurposeIn order to systematically grasp the changes and matching characteristics of wheel and rail profiles of high speed railway (HSR) in China, 172 rail profile measurement points and 384 wheels of 6 high-speed electric motive unites (EMUs) were selected on 6 typical HSR lines, including Beijing–Shanghai, Wuhan–Guangzhou, Harbin–Dalian, Lanzhou–Xinjiang, Guiyang–Guangzhou and Dandong–Dalian for a two-year field test.Design/methodology/approachBased on the measured data, the characteristics of rail and wheel wear were analyzed by mathematical statistics method. The equivalent conicity of wheel and rail matching in a wheel reprofiling cycle was analyzed by using the measured rail profile.FindingsResults showed that when the curve radius of HSR was larger than 2,495 m, the wear rate of straight line and curve rail was almost the same. For the line with annual traffic gross weight less than 11 Mt, the vertical wear of rail was less than 0.01 mm. The wear rate of the rail with the curve radius less than 800 m increased obviously. The wheel tread wear of EMUs on Harbin–Dalian line, Lanzhou–Xinjiang line and Dandong–Dalian line was relatively large, and the average wear rate of tread was about 0.05–0.06 mm·(10,000 km)−1, while that of Beijing–Shanghai line, Wuhan–Guangzhou line and Guiyang–Guangzhou line was about 0.03–0.035 mm·(10,000 km)−1. When the wear range was small, the equivalent conicity increased with the increase of wheel tread wear. When the wear range of wheel was wide, the wheel–rail contact points were evenly distributed, and the equivalent conicity did not increase obviously.Originality/valueThis research proposes the distribution range of the equivalent conicity in one reprofiling cycle of various EMU trains, which provides guidance for the condition-based wheel reprofiling.

Growth Regulators Improve Outcrossing Rate of Diverse Rice Cytoplasmic Male Sterile Lines through Affecting Floral Traits.

Cytoplasmic male sterility (CMS) provides an irreplaceable strategy for commercial exploitation of heterosis and producing high-yielding hybrid rice. The exogenous application of plant growth regulators could improve outcrossing rates of the CMS lines by affecting floral traits and accordingly increase hybrid rice seed production. The present study aimed at exploring the impact of growth regulators such as gibberellic acid (GA3), indole-3-acetic acid (IAA), and naphthalene acetic acid (NAA) on promoting floral traits and outcrossing rates in diverse rice CMS lines and improving hybrid rice seed production. The impact of foliar applications of growth regulators comprising GA3 at 300 g/ha or GA3 at 150 g/ha + IAA at 50 g/ha + NAA at 200 g/ha versus untreated control was investigated on floral, growth, and yield traits of five diverse CMS lines. The exogenously sprayed growth regulators, in particular, the combination of GA3, IAA, and NAA (T3) boosted all studied floral, growth, and yield traits in all tested CMS lines. Moreover, the evaluated CMS lines exhibited significant differences in all measured floral traits. L2, L3, and L1 displayed the uppermost spikelet opening angle, duration of spikelet opening, total stigma length, style length, stigma brush, and stigma width. In addition, these CMS lines exhibited the highest plant growth and yield traits, particularly under T3. Consequently, exogenous application of GA3, IAA, and NAA could be exploited to improve the floral, growth, and yield traits of promising CMS lines such as L2, L3, and L1, hence increasing outcrossing rates and hybrid rice seed production.

The Expression Level of ABCC6 Transporter in Colon Cancer Cells Correlates with the Activation of Different Intracellular Signaling Pathways.

The ATP-binding cassette sub-family C member 6 transporter (ABCC6) is mainly found in the basolateral plasma membrane of hepatic and kidney cells. In hepatocarcinoma HepG2 cells, ABCC6 was involved in cell migration. In the present study, we investigated the role of ABCC6 in colon cancer evaluating the effect of Quercetin and Probenecid, inhibitors of the ectonucleotidase NT5E and ABCC6, respectively, on migration rate of Caco2 and HT29 cell lines. Both drugs reduced cell migration analyzed by scratch test. Gene and protein expression were evaluated by quantitative reverse-transcription PCR (RT-qPCR) and Western blot, respectively. In Caco2 cells, in which ABCC6 is significantly expressed, the addition of ATP restored motility, suggesting the involvement of P2 receptors. Contrary to HT29 cells, where the expression of ABCC6 is negligible but remarkable to the level of NT5E, no effect of ATP addition was detected, suggesting a main role on their migration by the phosphatidylinositol 3′-kinase (PI3K)/Akt system. Therefore, in some colon cancers in which ABCC6 is overexpressed, it may have a primary role in controlling the extracellular purinergic system by feeding it with ATP, thus representing a potential target for a therapy aimed at mitigating invasiveness of those type of cancers.

A novel role for aspirin in enhancing the reprogramming function of miR-302/367 cluster and breast tumor suppression.

Recent studies have provided evidence for tumor suppressive function of the embryonic stem cell-specific miR-302/367 cluster through induction of a reprogramming process. Aspirin has been found to induce reprogramming factors of mesenchymal-to-epithelial transition in breast cancer cells. Therefore, we aimed to investigate whether overexpression of miR-302/367 cluster and aspirin treatment cooperate in the induction of reprogramming and tumor suppression in breast cancer cells. MDA-MB-231 and SK-BR-3 human breast cancer cell lines were transfected with a miR-302/367 expressing vector and treated with aspirin. The cells were evaluated for indices of apoptosis, proliferation, migration, and invasion. In both cell lines, treatment of miR-302/367-transfected cells with aspirin upregulated expression of some main pluripotency factors such as OCT4, SOX2, NANOG, and KLF4, and downregulated expression of some invasion and angiogenesis markers at gene and protein levels. Aspirin increased the apoptotic rate in both cell lines transfected with miR-302/367. Both miR-302/367 and aspirin upregulated the expression of FOXD3 protein which is a known inducer of OCT4 and NANOG. Our results demonstrate that aspirin can enhance miR-302/367-induced reprogramming of breast cancer cells possibly through upregulation of FOXD3 expression. This can further augment the reversal of epithelial-mesenchymal transition and inhibits migration, invasion, and angiogenic signaling in breast cancer cells reprogrammed by miR-302/367. Therefore, aspirin may serve as a useful adjuvant for reprogramming of cancer cells.

Energy Consumption Rate Evaluation Method Considering Occurrence of Defective Products and Misjudgment of Inspection Machine in Production Line

In recent years, reducing energy consumption has become a key issue in the industrial world. Therefore, industrial corporations must develop methods of pre-evaluation and production management for reducing their energy consumption while maintaining productivity. Moreover, production lines occasionally generate defective products, reducing the productivity and wasting energy, which affects the energy consumption per unit of production. These production lines require inspection machines to exclude defective products. The layout and configuration of inspection machines change when defective products are excluded, which affects the energy consumption per product. However, no methods have been developed for evaluating the energy consumption per product by considering the number of defective products and the layout and configuration of the inspection machines. In this study, we formulated the energy consumption rate of a production line that generates defective products as the production planning and management method. Specifically, we developed a formula for the energy consumption rate of a production line by considering the defect rate of its production machines and the layout and configuration of the inspection machines. A simulation involving a semiconductor manufacturing line was conducted to validate the proposed theory.

Demonstration of a highly bandwidth-efficient optical interconnection with symbol division multiplexing pulse amplitude modulation.

A novel symbol division multiplexing (SDM) technology is proposed in an intensity modulation and direct detection (IM/DD) pulse amplitude modulation (PAM) optical interconnection. The SDM-PAM4 symbol is the multiplexing of two standard 3-bit PAM8 symbols based on many-to-one (MTO) mapping, increasing by an extra 50% the line rate compared with a typical PAM4 under the same symbol rate and channel bandwidth. The forward error correction (FEC) based on low-density parity-check coding establishes a mechanism between the codewords of both intra- and inter-SDM-PAM4 symbols, to theoretically support the iterative decoding of symbol de-multiplexing employing an optimized bit-interleaved coded modulation iterative decoding (BICM-ID) system. Furthermore, since SDM evidently reduces the mapping order of the PAM signal, the transmission reliability can be effectively improved by alleviating the impairments mainly caused by fiber chromatic dispersion and Kerr nonlinearity. The experimental results indicate that the SDM-PAM4 can achieve more than 5 dB superior systematic receiver power sensitivity over 10-km single mode fiber transmission, and thus represent an important development in coding and modulation multiplexing techniques for optical interconnection systems.

Role of LOC_Os01g68450, Containing DUF2358, in Salt Tolerance Is Mediated via Adaptation of Absorbed Light Energy Dissipation.

Salt stress affects plant growth and productivity. In this study we determined the roles of eight genes involved in photosynthesis, using gene co-expression network analysis, under salt-stress conditions using Arabidopsis knockout mutants. The green area of the leaves was minimum in the at1g65230 mutant line. Rice LOC_Os01g68450, a homolog of at1g65230, was ectopically expressed in the at1g65230 mutant line to generate revertant lines. Under salt stress, the revertant lines exhibited significantly higher net photosynthesis rates than the at1g65230 mutant line. Moreover, the operating efficiency of photosystem II (PSII) and electron transport rate of the revertant lines were higher than those of the wild type and at1g65230 mutant line after 10 days of exposure to salt stress. After this period, the protein PsbD–the component of PSII–decreased in all lines tested without significant difference among them. However, the chlorophyll a and b, carotenoid, and anthocyanin contents of revertant lines were higher than those of the mutant line. Furthermore, lower maximum chlorophyll fluorescence was detected in the revertant lines. This suggests that LOC_Os01g68450 expression contributed to the salt tolerance phenotype by modifying the energy dissipation process and led to the ability to maintain photosynthesis under salt stress conditions.

Association of Diagnostic Stewardship for Blood Cultures in Critically Ill Children With Culture Rates, Antibiotic Use, and Patient Outcomes

Blood culture overuse in the pediatric intensive care unit (PICU) can lead to unnecessary antibiotic use and contribute to antibiotic resistance. Optimizing blood culture practices through diagnostic stewardship may reduce unnecessary blood cultures and antibiotics. To evaluate the association of a 14-site multidisciplinary PICU blood culture collaborative with culture rates, antibiotic use, and patient outcomes. This prospective quality improvement (QI) collaborative involved 14 PICUs across the United States from 2017 to 2020 for the Bright STAR (Testing Stewardship for Antibiotic Reduction) collaborative. Data were collected from each participating PICU and from the Children's Hospital Association Pediatric Health Information System for prespecified primary and secondary outcomes. A local QI program focusing on blood culture practices in the PICU (facilitated by a larger QI collaborative). The primary outcome was blood culture rates (per 1000 patient-days/mo). Secondary outcomes included broad-spectrum antibiotic use (total days of therapy and new initiations of broad-spectrum antibiotics ≥3 days after PICU admission) and PICU rates of central line-associated bloodstream infection (CLABSI), Clostridioides difficile infection, mortality, readmission, length of stay, sepsis, and severe sepsis/septic shock. Across the 14 PICUs, the blood culture rate was 149.4 per 1000 patient-days/mo preimplementation and 100.5 per 1000 patient-days/mo postimplementation, for a 33% relative reduction (95% CI, 26%-39%). Comparing the periods before and after implementation, the rate of broad-spectrum antibiotic use decreased from 506 days to 440 days per 1000 patient-days/mo, respectively, a 13% relative reduction (95% CI, 7%-19%). The broad-spectrum antibiotic initiation rate decreased from 58.1 to 53.6 initiations/1000 patient-days/mo, an 8% relative reduction (95% CI, 4%-11%). Rates of CLABSI decreased from 1.8 to 1.1 per 1000 central venous line days/mo, a 36% relative reduction (95% CI, 20%-49%). Mortality, length of stay, readmission, sepsis, and severe sepsis/septic shock were similar before and after implementation. Multidisciplinary diagnostic stewardship interventions can reduce blood culture and antibiotic use in the PICU. Future work will determine optimal strategies for wider-scale dissemination of diagnostic stewardship in this setting while monitoring patient safety and balancing measures.

Complementary Polarization-Diversity Coherent Receiver for Self-Coherent Homodyne Detection With Rapid Polarization Tracking

There has been renewed interest in coherent detection to provide high spectral efficiency transmission for short-reach optical interconnects. However, the expensive high-stable laser sources may preclude its potential application. To balance the high performance and low cost for short-reach optical networks, the self-coherent homodyne receiver has been investigated, where the dual-polarization (DP) signal and the remote local oscillator (LO) originating from the same laser source co-propagate over a duplex fiber, enabling a remarkable tolerance of laser linewidth. However, the fast evolution of the state of polarization (SOP) of remotely delivered LO becomes problematic for self-coherent homodyne detection systems. To combat the polarization wandering of the remote LO, the complicated adaptive/automatic polarization controller (APC) has been deployed with only up to a few hundred rad/s polarization tracking speed. In this paper, we propose a complementary polarization-diversity coherent receiver (C-PDCR) for self-coherent homodyne detection using remote LO. The proposed C-PDCR features rapid polarization tracking for remote LO utilizing electronic digital signal processing (DSP). The robustness of the proposed C-PDCR is verified and demonstrated with a 1.08-Tb/s line rate (net rate 769.4 Gb/s over 45-GHz electrical bandwidth) using DP PCS-256QAM signal under rapid polarization rotation rate up to 314 krad/s in the experiment, which is more than 3-orders improvement of magnitude compared to the prior reports.