42.6 Gbit/s fully integrated all-optical XOR gate

We demonstrate an SOA-based all-optical high-speed Mach-Zehnder interferometer exclusive- OR (XOR) gate fabricated in a silica III-V hybrid-integration technology platform.  The device includes integrated time delays for rapid differential operation as well as integrated phase shifters for fine tuning of power splitters and interferometer bias enabling highly optimized XOR gate operation.  XOR functionality is verified through inspection of the output pulse sequence and the carrier-suppressed output spectrum.  A 2.3 dB penalty for a 42.6 Gb/s RZ-OOK signal at a 10-9 bit error rate is observed

Use of semiconductor optical amplifiers in signal processing applications

We describe a 42.6 Gbit/s all-optical pattern recognition system which uses semiconductor optical amplifiers (SOAs). A circuit with three SOA-based logic gates is used to identify the presence of specific port numbers in an optical packet header

All-optical header processing in a 42.6Gb/s optoelectronic firewall

A novel architecture to enable future network security systems to provide effective protection in the context of continued traffic growth and the need to minimise energy consumption is proposed. It makes use of an all-optical pre-filtering stage operating at the line rate under software control to distribute incoming packets to specialised electronic processors. An experimental system that integrates software controls and electronic interfaces with an all-optical pattern recognition system has demonstrated the key functions required by the new architecture. As an example, the ability to sort packets arriving in a 42.6Gb/s data stream according to their service type was shown experimentally

Efficient interrogation method of forward Brillouin scattering in optical fibers using a narrow bandwidth long-period grating

A new technique for the characterization of the effective refractive index modulation in optical fibers due to transverse acoustic mode resonances excited by electrostriction is reported. Resonances excited by an optical pulse are probed by a narrow bandwidth longperiod grating (LPG) inscribed in the fiber, which is interrogated by a CW beam. The LPG used in this experiment has a narrow bandwidth and high sensitivity to small mode index perturbations, allowing the measurement of index variations from below 10-9 to 10-6. Radial and torsional-radial acoustic modes were characterized up to 1.1 GHz. The linewidth of resonances was found to be much shorter than in previous reports in which long fiber lengths are typically required, obtaining Q factors as high as 5000

Ophthalmology research in the UK’s National Health Service: the structure and performance of the NIHR’s Ophthalmology research portfolio

Purpose- To report on the composition and performance of the portfolio of Ophthalmology research studies in the United Kingdom’s National Institute for Health Research (NIHR) Clinical Research Network (UK CRN). Methods- Ophthalmology studies open to recruitment between 1 April 2010 and 31 March 2018 were classified by: sub-specialty, participant age, gender of Chief Investigator, involvement of genetic investigations, commercial/ non-commercial, interventional/observational design. Frequency distributions for each covariate and temporal variation in recruitment to time and target were analysed. Results- Over 8 years, 137,377 participants were recruited (average of 15,457 participants/year; range: 5485–32,573) with growth by year in proportion of commercial studies and hospital participation in England (76% in 2017/18). Fourteen percent of studies had a genetic component and most studies (82%) included only adults. The majority of studies (41%) enrolled patients with retinal diseases, followed by glaucoma (17%), anterior segment and cataract (13%), and ocular inflammation (6%). Overall, 68% of non-commercial studies and 55% of commercial studies recruited within the anticipated time set by the study and also recruited to or exceeded the target number of participants. Conclusions- High levels of clinical research activity, growth and improved performance have been observed in Ophthalmology in UK over the past 8 years. Some sub-specialties that carry substantial morbidity and a very high burden on NHS services are underrepresented and deserve more patient-centred research. Yet the NIHR and its CRN Ophthalmology National Specialty Group has enabled key steps in achieving the goal of embedding research into every day clinical care