Turbulence Characterisation for Free Space Optical Communication Using Off-Axis Digital Holography

An optical turbulence generator is characterised using digital holography, measuring the amplitude and phase of the perturbed optical field and enabling analysis of turbulence effects and development of mitigation techniques

11,700 km Transmission at 4.8 bit/4D-sym via Four-dimensional Geometrically-shaped Polarization-Ring-Switching Modulation

Using a novel geometrically-shaped four-dimensional modulation format, we transmitted 11x200 Gbit/s DWDM at 4.8 bit/4D-sym over 7,925 km and 11,700 km using EDFA-only and hybrid amplification, respectively. A reach increase of 16% is achieved over PM-8QAM.Comment: Contributed paper for OECC/PSC. Tue. Jul 9, 2019 9:00 AM - 10:30 AM JS

Immune Checkpoint Inhibitor-related Pancreatitis:A Case Series, Review of the Literature and an Expert Opinion

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of various malignancies, but are associated with serious adverse events like pancreatitis. Current guidelines are limited to the first step in treating acute ICI-related pancreatitis with steroids but lack treatment advices for steroid dependent pancreatitis. We describe a case series of 3 patients who developed ICI-related pancreatitis with chronic features such as exocrine insufficiency and pancreatic atrophy at imaging. Our first case developed after treatment with pembrolizumab. The pancreatitis responded well after discontinuation of immunotherapy but imaging showed pancreatic atrophy and exocrine pancreatic insufficiency persisted. Cases 2 and 3 developed after treatment with nivolumab. In both, pancreatitis responded well to steroids. However during steroid tapering, pancreatitis recurred and the latter developed exocrine pancreatic insufficiency and pancreatic atrophy at imaging. Our cases demonstrate resemblances with autoimmune pancreatitis based on clinical and imaging findings. In line, both diseases are T-cell mediated and for autoimmune pancreatitis azathioprine is considered as maintenance therapy. Guidelines of other T-cell mediated diseases like ICI-related hepatitis suggest tacrolimus. After adding tacrolimus in case 2 and azathioprine in case 3, steroids could be completely tapered and no new episodes of pancreatitis have occurred. These findings support the idea that the treatment modalities for other T-cell mediated diseases are worthwhile options for steroid dependent ICI-related pancreatitis.</p

30% Reach Increase via Low-complexity Hybrid HD/SD FEC and Nonlinearity-tolerant 4D Modulation

Current optical coherent transponders technology is driving data rates towards 1 Tb/s/{\lambda}and beyond. This trend requires both high-performance coded modulation schemes and efficient implementation of the forward-error-correction (FEC) decoder. A possible solution to this problem is combining advanced multidimensional modulation formats with low-complexity hybrid HD/SD FEC decoders. Following this rationale, in this paper we combine two recently introduced coded modulation techniques:the geometrically-shaped 4D-64 polarization ring-switched and the soft-aided bit-marking-scaled reliability decoder. This joint scheme enabled us to experimentally demonstrate the transmission of 11x218 Gbit/s channels over transatlantic distances at 5.2bit/4D-sym. Furthermore, a 30% reach increase is demonstrated over PM-8QAM and conventional HD-FEC decoding for product codes.Comment: This work has been submitted to IEEE Photonics Technology Letter

Receiver Calibration and Quantum Random Number Generation for Continuous-variable Quantum Key Distribution

The desire for secure communications and the advent of quantum computing has spurred innovation into key-distribution technologies that are secure against future quantum computers. Computationally secure solutions based on post quantum algorithms and physically-secure solutions using either discrete-variable or continuous-variable quantum key distribution (CV-QKD) have been proposed. The attraction with CV-QKD systems in particular is the potential to leverage the vast knowledge base and access scaling benefits of photonic integration for conventional coherent optical communication for key distribution. CV-QKD requires detailed characterization of coherent receiver hardware, specifically noise generated by electronics and shot noise caused by the local oscillator (LO) laser. This work investigates the temporal stability of the receiver noise power which defines the amount of trusted noise in the quantum link used to compute the secret key rate (SKR). Depending on the noise power’s stability, this characterization must be repeated often, typically in the order of seconds. Therefore, this work explores the possibility of using the shot noise measurement as a source of quantum random numbers, which is required by a CV-QKD transceiver. This work enables further integration of the CV-QKD hardware, removing the need for a separate quantum random number generator (QRNG)