Model-based end-to-end learning for a self-homodyne coherent system.

We investigate the statistical properties of the inherent intensity fluctuation in a low-cost and low-complexity self-homodyne coherent system employing an amplified spontaneous emission (ASE) source. The noise distribution model of the considered system is established, which is shown to be highly consistent with the experimental results for a 10 GBd 256-ary quadrature amplitude modulation (QAM) signal transmission over a 10 m duplex fiber. With the help of the proposed noise model, we then design advanced mappers and demappers. The optimized system alleviates the need for ASE bandwidth and is evaluated by applying forward error correction codes. Furthermore, we demonstrate an information rate increase of 6.67% with respect to 64-QAM.

Predictive Values of Pathological and Clinical Risk Factors for Positivity of Sentinel Lymph Node Biopsy in Thin Melanoma: A Systematic Review and Meta-Analysis.

BACKGROUND: The indications for sentinel lymph node biopsy (SLNB) for thin melanoma are still unclear. This meta-analysis aims to determine the positive rate of SLNB in thin melanoma and to summarize the predictive value of different high-risk features for positive results of SLNB. METHODS: Four databases were searched for literature on SLNB performed in patients with thin melanoma published between January 2000 and December 2020. The overall positive rate and positive rate of each high-risk feature were calculated and obtained with 95% confidence intervals (CIs). Both unadjusted odds ratios (ORs) and adjusted ORs (AORs) of high-risk features were analyzed. Pooled effects were estimated using random-effects model meta-analyses. RESULTS: Sixty-six studies reporting 38,844 patients with thin melanoma who underwent SLNB met the inclusion criteria. The pooled positive rate of SLNB was 5.1% [95% confidence interval (CI) 4.9%-5.3%]. Features significantly predicted a positive result of SLNB were thickness≥0.8 mm [AOR 1.94 (95%CI 1.28-2.95); positive rate 7.0% (95%CI 6.0-8.0%)]; ulceration [AOR 3.09 (95%CI 1.75-5.44); positive rate 4.2% (95%CI 1.8-7.2%)]; mitosis rate >0/mm2 [AOR 1.63 (95%CI 1.13-2.36); positive rate 7.7% (95%CI 6.3-9.1%)]; microsatellites [OR 3.8 (95%CI 1.38-10.47); positive rate 16.6% (95%CI 2.4-36.6%)]; and vertical growth phase [OR 2.76 (95%CI 1.72-4.43); positive rate 8.1% (95%CI 6.3-10.1%)]. CONCLUSIONS: The overall positive rate of SLNB in thin melanoma was 5.1%. The strongest predictor for SLN positivity identified was microsatellites on unadjusted analysis and ulceration on adjusted analysis. Breslow thickness ≥0.8 mm and mitosis rate >0/mm2 both predict SLN positivity in adjusted analysis and increase the positive rate to 7.0% and 7.7%. We suggest patients with thin melanoma with the above high-risk features should be considered for giving an SLNB.

Efficacy and safety of botulinum toxin type A for postoperative scar prevention and wound healing improvement: A systematic review and meta-analysis.

BACKGROUND: Botulinum toxin type A (BTXA) has shown underlying effects for wound healing improvement. New small clinical trials keep emerging every year and updated evidence-based information is warranted. This study aimed to evaluate the efficacy and safety of BTXA for preventing scarring. METHODS: Four databases were searched to recruit randomized clinical trials (RCTs) which compared the surgical wounds treated with BTXA vs. those treated with placebo or blank control. The outcomes were primarily quantified by measures including the Vancouver Scar Scale (VSS), Visual Analog Scale (VAS), Stony Brook Scar Evaluation Scales (SBSES), modified SBSES (mSBSES), and scar width. Patients' satisfaction and adverse events were also reported. RESULTS: In total, 16 RCTs involving 671 cases (510 patients) were included. The outcome showed significant superiority of BTXA in VSS (mean difference [MD] = -1.32, 95% confidence interval [CI]: -2.00 to -0.65, p = 0.0001), VAS (MD = 1.29, 95% CI: 1.05-1.52, p < 0.00001), SBSES or mSBSES (MD = -0.18, 95% CI: -0.27 to -0.10, p < 0.0001), scar width (MD = -0.18, 95% CI: -0.27 to -0.10, p < 0.0001), and patients' satisfaction (risk ratio [RR] = 1.25, 95% CI: 1.06-1.49, p = 0.01). No significant difference of adverse events incidence was observed (RR = 1.46 95% CI: 0.64-3.33, p = 0.36). CONCLUSIONS: Botulinum toxin type A is effective and safe for postoperative scar prevention and wound healing improvement, especially for facial wounds of Asians. Further studies should manage to standardize the treatment algorithm, while mSBSES is recommended for scar assessment.

Demonstration of terabit coherent on-chip optical interconnects employing mode-division multiplexing.

We experimentally demonstrate a net capacity per wavelength of 1.23 Tb/s with 30 GBaud 16-ary quadrature amplitude modulation (16-QAM) mode-division multiplexing (MDM) signals over a single silicon-on-insulator (SOI) multimode waveguide for optical interconnects employing $11 \times 11$ multiple-in-multiple-out (MIMO) digital signal processing. In order to simplify the receiver architecture for coherent optical interconnects, we further propose and evaluate an on-chip self-homodyne coherent detection (SHCD) scheme. In the experiment, 30 Gbaud quadrature phase shift keying (QPSK) signals carried by 10 waveguide modes are successfully recovered with bit error rates (BERs) below 7% forward error correction (FEC) threshold using the pilot tone delivered by ${{\rm TE}_0}$ mode as a local oscillator. Around 10% penalty on error vector magnitude (EVM) is observed due to modal cross talk compared to homodyne detection.

Carrier-less phase retrieval receiver leveraging digital upsampling.

Phase retrieval (PR) receivers can reconstruct the full electrical field of the signal using only intensity measurements without any optical carrier. In this Letter, we investigate the requirement of digital upsampling and receiver bandwidth of the PR receiver based on alternative projection employing a dispersive element. An iteration scheme averaging the interleaved upsampled symbols to maintain two samples per symbol for the estimated complex-valued signal is proposed and experimentally demonstrated with fast algorithm convergence. The PR uses a modified Gerchberg-Saxton algorithm. Experimentally, we measure Nyquist-shaped 30-GBaud quadrature phase shift keying signals after 55-km single-mode fiber transmission using only 110 and 250 iterations to reach, respectively, the 20% and 7% forward-error correction threshold levels.

Phase retrieval with fast convergence employing parallel alternative projections and phase reset for coherent communications.

Phase-retrieval (PR) receivers can reconstruct complex-valued signals using only direct detection without the use of any optical carriers. We propose and demonstrate two PR receiver solutions with faster and better convergence. First, we demonstrate a PR receiver based on parallel alternative projections that are produced by propagating the signal through an array of dispersive elements of increasing length followed by direct detection. Fast convergence and high retrieved phase accuracy are achieved using a modified Gerchberg-Saxton (GS) algorithm that uses each projection as an intensity constraint. Second, we achieve similar performances employing an enhanced single projection GS algorithm with selective phase reset using symbol-wise GS errors. We experimentally reconstruct a 30 Gbaud QPSK signal after 55 km single-mode fiber transmission using the proposed solutions with a reduced number of iterations.

Temporal and spectral coding over amplified spontaneous emission for secure optical coherent communications.

We demonstrate secure optical coherent communications employing low-coherence matched detection based on the randomness of amplified spontaneous emission (ASE) noise. Two-level physical-layer optical encryption is achieved through temporal and spectral coding over a broadband ASE source. An ASE-carried signal and unmodulated carrier are polarization multiplexed, transmitted over a same single-mode fiber (SMF), and separated with the aid of polarization tracking before having matched detection at the receiving side. The impact of chromatic dispersion on the low-coherence matched detection system is analyzed and experimentally investigated. We experimentally realize optically coded 20 Gbaud QPSK and 8-PSK signals transmission over a 43 km SMF span with a maximum line rate of 60 Gbits/s.