In anticipation of emerging applications such as business services, 5G, and the Internet of Things, research and standardization are working together towards next-generation 25/50 Gbit/s passive optical network access networks. However, the increase in single-channel line rate is limited by the distortion introduced by the low-cost device's bandwidth limit or the chromatic dispersion in the fiber. Burst-mode electronic distortion/dispersion compensation can be used to mitigate these effects, but requires a burst-mode equalizer (BMEQ) for upstream traffic and introduces many challenges. In this invited paper, the feasibility of single-channel, directly modulated upstream 25 Gbit/s non-return-to-zero transmission is investigated in more detail. By using a linear burst-mode transimpedance amplifier together with an offline BMEQ, specific BMEQ penalties and trade-offs such as limited training time and burst-to-burst phase variation are considered. (C) 2019 Optical Society of America

We present optical coupling schemes for silicon integrated photonics circuits that account for the challenges in large-scale data processing systems such as those used for emerging big data workloads. Our waveguide based approach allows to optimally exploit the on-chip optical feature size, and chip-and package real-estate. It further scales well to high numbers of channels and is compatible with state-of-the-art flip-chip die packaging. We demonstrate silicon waveguide to polymer waveguide coupling losses below 1.5 dB for both the O- and C-bands with a polarisation dependent loss of < 1 dB. Over 100 optical silicon waveguide to polymer waveguide interfaces were assembled within a single alignment step, resulting in a physical I/O channel density of up to 13 waveguides per millimetre along the chip-edge, with an average coupling loss of below 3.4 dB measured at 1310 nm.

Optically transparent polymer waveguides are employed for interfacing silicon photonics devices to fibers. The highly confined optical mode in the nanophotonic silicon waveguide is transferred to a fiber-matched polymer waveguide through adiabatic optical coupling by tapering the silicon waveguide. The polymer waveguides are either processed onto the silicon photonics wafer or bonded to individual chips. Fibers are interfaced to the polymer waveguides through butt-coupling. We show polarization and wavelength-tolerant fiber-to-chip coupling loss of less than 3.5 dB across the O-band. The polymer waveguide-to-silicon-chip alignment tolerance is 2 mu m for a loss increase of only 1 dB. Reflection losses are well below -45 dB and the scalability to large numbers of channels is demonstrated. These results open a path to broadband and polarization-tolerant optical packaging of silicon photonics devices for ultrahigh bandwidth applications employing wavelength division multiplexing across multiple channels as envisioned for future data-center interconnects.

We demonstrate for the first time that a single compact, electrically contacted indium phosphide based microdisk heterogeneously integrated on a silicon-on-insulator waveguide can be used as both a highspeed modulator and photo detector. We demonstrate high-speed operation up to 10 Gb/s and present bit-error rate results of both operation modes. (C)2012 Optical Society of America

A novel concept for an arrayed-waveguide-grating (AWG)-based fast tunable laser is presented. It is fabricated in the InP-InGaAsP monolithic integration technology. Laser peaks have a sidemode suppression ratio of 30-40 dB. The wavelength switching speed is in the order of a few nanoseconds and switching is achieved by a 1-mA bias current. The switching between AWG channels is discrete and no laser operation takes place at wavelengths corresponding to other channels during the tuning process.

Portal vein thrombosis (PVT) is a serious complication of end-stage liver disease, representing a challenge for the liver transplantation (LT) team. The aim of this study was to analyze the results of LT in patients with PVT. Methods: All adult patients who underwent a LT from a cadaveric donor between March 1994 and March 2010 were included. PVT was categorized using the classification of Yerdel and McMaster. Results: A total of 109 LT were performed in 105 patients. PVT was found in 13 cases (12.4%). In 6 of them (46.2%), thrombosis was found preoperatively by transplant routine work up. Pre-transplant systemic anticoagulation was indicated in 3 cases. At the time of surgery, only 10 patients had persistent PVT. Grade I, II, III and IV PVT was found on 2, 3, 4 and 1 patient respectively. In the 3 cases treated with systemic anticoagulation preo-peratively, grade I (1 case) and grade II (2 cases) no thrombus was evident intraoperatively. Endovenectomy was performed in 7 cases; simple thrombectomy in one and a mesenteric vein graft was required in 2 cases. No thrombus recurrence was detected on postoperative follow-up. In-hospital mortality occurred in 2 cases with PTV grade III and IV due to medical complications. One-year patient and graft survival was 69% vs 79% in patients without PVT (p = 0,476). Conclusion: Liver transplant in patients with PVT thrombosis was not associated with a significant increased risk of mortality. Systemic anticoagulation seems to be warranted while waiting for liver transplantation.