Research and design of high-speed advanced analogue front-ends for fibre-optic transmission systems

In the last decade, we have witnessed the emergence of large, warehouse-scale data centres which have enabled new internet-based software applications such as cloud computing, search engines, social media, e-government etc. Such data centres consist of large collections of servers interconnected using short-reach (reach up to a few hundred meters) optical interconnect. Today, transceivers for these applications achieve up to 100Gb/s by multiplexing 10x 10Gb/s or 4x 25Gb/s channels. In the near future however, data centre operators have expressed a need for optical links which can support 400Gb/s up to 1Tb/s. The crucial challenge is to achieve this in the same footprint (same transceiver module) and with similar power consumption as today’s technology. Straightforward scaling of the currently used space or wavelength division multiplexing may be difficult to achieve: indeed a 1Tb/s transceiver would require integration of 40 VCSELs (vertical cavity surface emitting laser diode, widely used for short‐reach optical interconnect), 40 photodiodes and the electronics operating at 25Gb/s in the same module as today’s 100Gb/s transceiver. Pushing the bit rate on such links beyond today’s commercially available 100Gb/s/fibre will require new generations of VCSELs and their driver and receiver electronics. This work looks into a number of state‐of-the-art technologies and investigates their performance restraints and recommends different set of designs, specifically targeting multilevel modulation formats. Several methods to extend the bandwidth using deep submicron (65nm and 28nm) CMOS technology are explored in this work, while also maintaining a focus upon reducing power consumption and chip area. The techniques used were pre-emphasis in rising and falling edges of the signal and bandwidth extensions by inductive peaking and different local feedback techniques. These techniques have been applied to a transmitter and receiver developed for advanced modulation formats such as PAM-4 (4 level pulse amplitude modulation). Such modulation format can increase the throughput per individual channel, which helps to overcome the challenges mentioned above to realize 400Gb/s to 1Tb/s transceivers.

Ontological representation of design science research publications

A search result provided by existing digital library and web search systems typically comprises only a prioritised list of possible publications or web pages that meet the search criteria, possibly with excerpts and possibly with search terms highlighted. The research in progress reported in this poster contributes to a larger research effort to provide a readable summary of search results that synthesise relevant publications or web pages to provide results that meet four C’s: comprehensive, concise, coherent, and correct, as a more useful alternative to un-synthesised result lists. The scope of this research is limited to searching for and synthesising Design Science Research (DSR) publications that present the results of DSR, as an example problem domain.

Adult orthodontics: internet information and a national survey

Aims: 1. To investigate the reliability and readability of information on the Internet on adult orthodontics. 2. To evaluate the profile and treatment of adults by specialist orthodontists in the Republic of Ireland (ROI). Materials and methods: 1. An Internet search was conducted in May 2015 using three search engines (Google, Yahoo and Bing), with two search terms (“adult orthodontics” and “adult braces”). The first 50 websites from each engine were screened and exclusion criteria applied. Included websites were then assessed for reliability using the JAMA benchmarks, the DISCERN and LIDA tools and the presence of the HON seal. Readability was assessed using the FRES. 2. A pilot-tested questionnaire about adult orthodontics was distributed to 122 eligible specialist orthodontists in the ROI. Questions addressed general and treatment information about adult orthodontic patients, methods of information provision and respondent demographics. Results: 1. Thirteen websites met the inclusion criteria. Three websites contained all JAMA benchmarks and one displayed the HON Seal. The mean overall score for DISCERN was 3.9/5 and the mean total LIDA score was 115/120. The average FRES score was 63.1. 2. The questionnaire yielded a response rate of 83%. The typical demographic profile of adult orthodontic patients was professional females between 25-35 years. The most common incisor relationship and skeletal base was Class II, division 1 (51%) and Class II (61%) respectively. Aesthetic upper brackets and metal lower brackets were the most frequently used appliances. Only 30% of orthodontists advise their adult patients to find extra information on the Internet. Conclusions: 1. The reliability and readability of information on the Internet on adult orthodontics is of moderate quality. 2. The provision of adult orthodontic treatment is common among specialist orthodontists in the Republic of Ireland.