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5G defines below 100 GHz as the millimeter-wave bands, whereas 100 GHz - 3 THz is categorized as THz band in 6G. Deep leraning (DL) is expected to enable a significant paradigm shift in 6G wireless networks. In this paper, D-band 90-Gbps single channel PAM-4 signal generation and transmission over 10-km SMF and 3-m wireless link at 140-GHz can be achieved. A novel complex-valued neural network (CVNN) equalizer using ‘CReLU’ activation function to directly recover PAM-4 signals from received noised signals is demonstrated. There are three DSP options in the experiment. In Opt .1, firstly conducted cascaded multi-modulus algorithm (CMMA) pre-equalization (pre-EQ) at transmitter, then processed via frequency offset estimation (FOE), carrier phase recovery (CPR) and finally real-valued neural network (RVNN) equalization at receiver. Here, the RVNN equalizers include DNN with a softmax output layer, two-step joint-DNN equalizer and LSTM. The experimental results show that LSTM-based equalizer outperforms the other real NN-based equalizers by average 0.5 to 1.5 dB at BER of 10−3 magnitude. Differently from Opt . 1, real-valued CMMA pre-EQ at transmitter is unexpected for CVNN in the other two options. In Opt . 2, we only combine down-conversion and CVNN regarded as ‘pure data-driven’ training at receiver. This pure data-driven CVNN equalizer improves BER a lot and also has a larger computation burden, especially BER is as low as 1 × 10−4 with n 0 = 571 and n 1 = 200 training cells and the time complexity reaches 350000 in one iteration. Thanks to the aid of traditional mathematical-oriented models including FOE and CPR, the computation burden of CVNN in Opt . 3 is released significantly. Furthermore, we compare the performance of CVNN and RVNN in terms of BER decision accuracy, time complexity and receiver sensitivity. Followed by the same DSP with the same complexity, the comparison result between DNN and CVNN in the same structure of [371-260-1] with 11000 samples and 300 epochs shows that CVNN performs better due to its reservation of phase information. Therefore, we believe that the joint use of model-based, e.g., FOE, CPR steps and complex DL-based techniques has a potential for the future 6G wireless physical layer algorithms.

The transmission of a 65,536-ary quadrature amplitude modulation (QAM) orthogonal frequency division multiplexing (OFDM) signal supported by a hybrid fiber–terahertz (THz) multiple-input multiple-output (MIMO) system at 320 GHz is experimentally demonstrated in this Letter. We adopt the polarization division multiplexing (PDM) technique to double the spectral efficiency. Based on a 23-GBaud 16-QAM link, 2-bit delta-sigma modulation (DSM) quantization enables 65,536-QAM OFDM signal transmission over a 20-km standard single-mode fiber (SSMF) and a 3-m 2 × 2 MIMO wireless delivery, and satisfies the hard-decision forward error correction (HD-FEC) threshold of 3.8 × 10−3, corresponding to a net rate of 60.5 Gbit/s for THz-over-fiber transport. Meanwhile, below the fronthaul error vector magnitude (EVM) threshold of 0.34%, a maximum signal-to-noise ratio (SNR) of 52.6 dB is achieved. To the best of our knowledge, this is the highest modulation order achievable for DSM applications in THz communication.

We experimentally demonstrated a low-complexity probabilistic shaping (PS) 16-ary quadrature amplitude modulation (16QAM) scheme based on intra-symbol bit-weighted distribution matching (Intra-SBWDM) for discrete multi-tone (DMT) symbols with field-programmable gate array implementation in an intensity modulation and direct detection (IM-DD) system. Different from the traditional PS scheme such as Gallager many-to-one mapping, hierarchical distribution matching and constant composition distribution matching, the Intra-SBWDM scheme with lower computation and hardware complexity does not need to continuously refine the interval to find the target symbol probability, nor does it need a look-up table, so it does not introduce a large number of extra redundant bits. In our experiment, four PS parameter values (k = 4, 5, 6, and 7) are investigated in a real-time short-reach IM-DD system. 31.87-Gbit/s net bit PS-16QAM-DMT (k = 4) signal transmission is achieved. The results show that the receiver sensitivity in terms of the received optical power of the real-time PS scheme based on Intra-SBWDM (k = 4) over OBTB/20 km standard single-mode fiber can be improved by about 1.8/2.2 dB at the bit error rate (BER) of 3.8 × 10−3, compared to the uniformly-distributed DMT. In addition, the BER is steadily lower than 3.8 × 10−3 during a one-hour measurement for PS-DMT transmission system.

We experimentally demonstrated a 5-channel 125-GHz-grid wavelength division multiplexing (WDM) transmission over 6,400-km Raman amplified ultra large effective area fiber (ULAF) with 848-Gbps/carrier line-rate and 640-Gbps/carrier net-bit-rate. Our transmission is based on probabilistically shaped (PS) dual-polarization 16-ary quadrature-amplitude-modulation (16QAM) considering 25%-overhead low-density parity-check threshold of 4.6 × 10−2 bit-error-rate. By utilizing a high-speed digital-analog-converter (DAC) with a 3-dB bandwidth of 35 GHz and innovative pre-equalization based on 4-level pulse-amplitude-modulation (PAM4), 106-Gbaud 16QAM signal is reliably generated and transmitted. Besides, the transmission distance is improved obviously by using ULAF and Raman amplifier. Our results show that the PS-16QAM outperforms the regular-16QAM by around 1.5-dB sensitivity gain and 33% transmission-distance improvement. Furthermore, we have successfully applied Volterra nonlinear equalization (VNLE) to ultra-long-haul coherent optical transmission and proposed a modified offline digital-signal-processing process. By utilizing VNLE, another 15% reach improvement is obtained for PS-16QAM signal. Our work can provide an effective solution for a 600G+ ultra-long-haul transmission. As we know, this is the first time to achieve 640-Gbps/carrier WDM transmission over 6,400 km based on 106-Gbaud PS-16QAM.

An efficient nonlinear equalizer based on the pruning I/Q-joint deep neural network (DNN) is proposed and experimentally demonstrated to mitigate the nonlinearity in a photonics-assisted millimeter-wave (MMW) system with a high-order 256 quadrature-amplitude-modulation (QAM) format. Experimental findings reveal that implementing pruning on the I/Q-joint DNN can compress the computational overhead by 32% while accommodating 256-QAM E-band MMW transmission for a net throughput of 66.67 Gbps with 20.21% less complexity than the traditional Volterra nonlinear equalizer. Compared with the I/Q dual DNN with the same complexity, a 16% pruning ratio improvement is enabled by a robust pruning I/Q-joint DNN that further deciphers the I/Q relationship.

We experimentally demonstrated a 125-GHz-grid WDM coherent transmission over 2,000-km Raman amplified ULAF with 800-Gbit/s/carrier net-bit-rate based on 100-Gbaud truncated PS-64QAM. Our results show that the MIMO-VNLE outperforms the SISO-VNLE by around 67% reach improvement.

In this paper, a novel scheme to employ one external polarization division multiplexing Mach–Zehnder Modulator (PDM-MZM) and one polarizer to generate millimeter-wave four-level pulse amplitude modulation (PAM4) signal is proposed without the usage of expensive and power hungry digital-to-analog converter (DAC). Firstly, we theoretically derive the generation conditions for the mm-wave PAM4 signal scheme. Based on this cost-effective scheme, 6 Gbaud PAM4 signal carried by 84 GHz millimeter-wave transmission over 15 km single-mode fiber (SMF-28) with only 0.5 dB power penalty without any CD compensation is experimentally demonstrated. Furthermore, VPI simulation software is employed to numerically simulate the mm-wave PAM4 signal generation and explore the influences of polarization rotation of the polarizer and direct current (DC)-Bias on the performance of generated W-band signals. In a word, it would be a promising scheme for future 5G short-reach intensity modulation and direct detection (IM/DD) system.

The glass forming ability (GFA) and thermodynamic properties of the La-Al-Cu-Co alloy system were investigated, and novel La-Al-Cu-Co bulk metallic glasses (BMGs) with a minimum critical diameter of 8 mm were fabricated. The differing GFAs were examined from a thermodynamic viewpoint. The GFA of the La-Al-Cu-Co alloys was well-correlated with the supercooled liquid region, ΔTx, and the parameter, γ; but not with the reduced glass transition temperature, Trg. In addition, the La62Al14Cu14Co8 BMG exhibited a high GFA, low glass transition temperature of 412 K, and broad supercooled liquid region of 70 K. These novel BMGs, which were fabricated from low-cost raw materials, had the potential to be used in various applications. The GFA of the present alloys exhibited a dependence on the relative number of Al–Co and Al–Cu atomic pairs, i.e., on the Al:Co and Al:Cu ratios, which were ∼2.3 and 0.85, respectively.

The aim of this study was to report the efficacy and safety of applying pupilloplasty in combination with Artisan iris-fixated intraocular lens (IOL) implantation in the treatment for aphakia with pathologically large pupil and insufficient capsular support.The study was a retrospective case series.Twenty-six aphakic eyes with pathologically large pupil and insufficient capsular support (from 26 patients) were included in the study.The study patients underwent pupilloplasty in combination with Artisan iris-fixated IOL implantation. Follow-up appointments were scheduled at 1 week and at 1, 3, and 6 months postoperatively.The mean uncorrected visual acuity was significantly improved from logMAR 1.15 ± 0.29 to logMAR 0.37 ± 0.17, and the mean manifest refraction spherical equivalent was significantly decreased from 12.07 ± 2.20 D to -0.69 ± 0.70 D at 6 month after surgery (p0.05). The pupil diameter decreased significantly, from 5.7 ± 1.1 mm preoperatively to 4.5 ± 0.8 mm at 6 months after pupilloplasty (p0.05). Patients experienced less photophobia postoperatively. The safety parameters, including endothelial cell count, intraocular pressure, corneal astigmatism, best-corrected visual acuity, and central corneal thickness, showed no significant differences in values before and after surgery.The Artisan iris-fixated IOL implantation in combination with pupilloplasty can be used as an alternative way to correct aphakia with pathologically large pupil and insufficient capsular support.

Background: To evaluate the visual outcomes of conductive keratoplasty for relief of symptomatic presbyopia of pseudophakia with monofocal intraocular lens implantation. Design: It was a prospective clinical study and set in Eye Center, Second Affiliated Hospital, Zhejiang University. Participants: This study comprised 27 eyes from 27 patients with presbyopia symptom. Methods: The patients received conductive keratoplasty via monovision approach after monofocal intraocular lens implantation and were followed up at 1 week and 1, 3, 6 and 12 months postoperatively. Main Outcome Measures: The main outcomes including uncorrected near visual acuity, uncorrected distance visual acuity, best spectacle-corrected visual acuity, manifest refraction spherical equivalent, keratometric astigmatism, contrast and glare sensitivity, spherical aberration and pseudoaccommodation were evaluated. Results: Twelve months after conductive keratoplasty, the binocular uncorrected near visual acuity was significantly improved from logMAR 0.88 ± 0.16 preoperatively to logMAR 0.30 ± 0.13 (P

Retinal neovascularization is one of the leading causes for complete blindness in a number of diseases around the world. Endostar, a recently introduced recombinant human endostatin, has been considered as one of the most valuable anti-angiogenic agents. In this study, we demonstrate that Endostar inhibits both the proliferation of the choroid-retinal endothelial cells through limiting the progression of the cell cycle and their migration. Furthermore, Endostar induces the expression of the pigment epithelial-derived factor (PEDF) and suppresses the expression of the vascular endothelial growth factor (VEGF) and the fibroblast growth factor (FGF). Endostar also reduces the expression of the inflammatory mediator tumor necrosis factor-alpha (TNF-alpha), matrix metalloproteinases (MMPs) and vascular cell adhesion molecule-1 (VCAM-1). These findings reveal an integrated role of Endostar in the program of retinal vascular control and highlight its significant potential for broad clinical application.

In this study, we evaluated the impact of preoperative high mobility group box 1 (HMGB1) on myocardial injury post-percutaneous coronary intervention. We evaluated 302 consecutive patients who underwent percutaneous coronary intervention. They were divided into equal tertiles based on their preoperative HMGB1 levels. Creatine kinase-MB and troponin I levels were measured at baseline, 8- and 24-hours after the procedure, while clinical outcomes were followed up for 1 year. The occurrence of post-procedural myocardial injury was significantly higher in the tertile comprising of patients with elevated HMGB1 levels. Moreover, these patients showed significantly higher post-procedural peak values of creatine kinase-MB and troponin I in comparison to patients with lower HMGB1 levels. Event-free survival was significantly associated with HMGB1 levels, with worst event-free survival in patients with elevated HMGB1 levels. Elevated preoperative HMGB1 was a predictor of myocardial injury after percutaneous coronary intervention, and was associated with the worst clinical outcomes during 1-year follow up.

To evaluate the visual outcomes of conductive keratoplasty for relief of symptomatic presbyopia of pseudophakia with monofocal intraocular lens implantation.It was a prospective clinical study and set in Eye Center, Second Affiliated Hospital, Zhejiang University.This study comprised 27 eyes from 27 patients with presbyopia symptom.The patients received conductive keratoplasty via monovision approach after monofocal intraocular lens implantation and were followed up at 1 week and 1, 3, 6 and 12 months postoperatively.The main outcomes including uncorrected near visual acuity, uncorrected distance visual acuity, best spectacle-corrected visual acuity, manifest refraction spherical equivalent, keratometric astigmatism, contrast and glare sensitivity, spherical aberration and pseudoaccommodation were evaluated.Twelve months after conductive keratoplasty, the binocular uncorrected near visual acuity was significantly improved from logMAR 0.88 ± 0.16 preoperatively to logMAR 0.30 ± 0.13 (P0.05); the binocular uncorrected distance visual acuity and best spectacle-corrected visual acuity remained unchanged; manifest refraction spherical equivalent was significantly reduced from 0.01 ± 0.68 D preoperatively to -1.68 ± 0.39 D (P0.05); spherical aberration was increased from 0.266 ± 0.204 µm preoperatively to 0.358 ± 0.277 µm (P0.05), and pseudoaccommodation was from 1.38 ± 0.38 D to 1.73 ± 0.61 D (P0.05).Conductive keratoplasty is a safe and effective method for relief of symptomatic presbyopia of pseudophakia with monofocal intraocular lens implantation.