Numerical modelling of devices and advanced transmission schemes embracing Raman effect

This thesis presents a theoretical investigation on applications of Raman effect in optical fibre communication as well as the design and optimisation of various Raman based devices and transmission schemes. The techniques used are mainly based on numerical modelling. The results presented in this thesis are divided into three main parts. First, novel designs of Raman fibre lasers (RFLs) based on Phosphosilicate core fibre are analysed and optimised for efficiency by using a discrete power balance model. The designs include a two stage RFL based on Phosphosilicate core fibre for telecommunication applications, a composite RFL for the 1.6 μm spectral window, and a multiple output wavelength RFL aimed to be used as a compact pump source for fiat gain Raman amplifiers. The use of Phosphosilicate core fibre is proven to effectively reduce the design complexity and hence leads to a better efficiency, stability and potentially lower cost. Second, the generalised Raman amplified gain model approach based on the power balance analysis and direct numerical simulation is developed. The approach can be used to effectively simulate optical transmission systems with distributed Raman amplification. Last, the potential employment of a hybrid amplification scheme, which is a combination between a distributed Raman amplifier and Erbium doped amplifier, is investigated by using the generalised Raman amplified gain model. The analysis focuses on the use of the scheme to upgrade a standard fibre network to 40 Gb/s system.

Writing and characterisation methods for UV-photosensitivity based devices and their applications

The underlying work to this thesis focused on the exploitation and investigation of photosensitivity mechanisms in optical fibres and planar waveguides for the fabrication of advanced integrated optical devices for telecoms and sensing applications. One major scope is the improvement of grating fabrication specifications by introducing new writing techniques and the use of advanced characterisation methods for grating testing. For the first time the polarisation control method for advanced grating fabrication has successfully been converted to apodised planar waveguide fabrication and the development of a holographic method for the inscription of chirped gratings at arbitrary wavelength is presented. The latter resulted in the fabrication of gratings for pulse-width suppression and wavelength selection in diode lasers. In co-operation with research partners a number of samples were tested using optical frequency domain and optical low coherence reflectometry for a better insight into the limitations of grating writing techniques. Using a variety of different fabrication methods, custom apodised and chirped fibre Bragg gratings were written for the use as filter elements for multiplexer-demultiplexer devices, as well as for short pulse generation and wavelength selection in telecommunication transmission systems. Long period grating based devices in standard, speciality and tapered fibres are presented, showing great potential for multi-parameter sensing. One particular scope is the development of vectorial curvature and refractive index sensors with potential for medical, chemical and biological sensing. In addition the design of an optically tunable Mach-Zehnder based multiwavelength filter is introduced. The discovery of a Type IA grating type through overexposure of hydrogen loaded standard and Boron-Germanium co-doped fibres strengthened the assumption of UV-photosensitivity being a highly non-linear process. Gratings of this type show a significantly lower thermal sensitivity compared to standard gratings, which makes them useful for sensing applications. An Oxford Lasers copper-vapour laser operating at 255 nm in pulsed mode was used for their inscription, in contrast to previous work using CW-Argon-Ion lasers and contributing to differences in the processes of the photorefractive index change

Recent advances in fibre grating devices and their sensing applications

Over the last twenty years, we have been continuously seeing R&D efforts and activities in developing optical fibre grating devices and technologies and exploring their applications for telecommunications, optical signal processing and smart sensing, and recently for medical care and biophotonics. In addition, we have also witnessed successful commercialisation of these R&Ds, especially in the area of fibre Bragg grating (FBG) based distributed sensor network systems and technologies for engineering structure monitoring in industrial sectors such as oil, energy and civil engineering. Despite countless published reports and papers and commercial realisation, we are still seeing significant and novel research activities in this area. This invited paper will give an overview on recent advances in fibre grating devices and their sensing applications with a focus on novel fibre gratings and their functions and grating structures in speciality fibres. The most recent developments in (i) femtosecond inscription for microfluidic/grating devices, (2) tilted grating based novel polarisation devices and (3) dual-peak long-period grating based DNA hybridisation sensors will be discussed.

An exploration of the determinants of innovation:the top management team, organisational climate and organisational learning

Some researchers argue that the top team, rather than the CEO, is a better predictor of an organisation’s fate (Finkelstein & Hambrick, 1996; Knight et al., 1999). However, others suggest that the importance of the top management team (TMT) composition literature is exaggerated (West & Schwenk, 1996). This has stimulated a need for further research on TMTs. While the importance of TMT is well documented in the innovation literature, the organisational environment also plays a key role in determining organisational outcomes. Therefore, the inclusion of both TMT characteristics and organisational variables (climate and organisational learning) in this study provides a more holistic picture of innovation. The research methodologies employed includes (i) interviews with TMT members in 35 Irish software companies (ii) a survey completed by managerial respondents and core workers in these companies (iii) in-depth interviews with TMT members from five companies. Data were gathered in two phases, time 1 (1998-2000) and time 2 (2003). The TMT played an important part in fostering innovation. However, it was a group process, rather than team demography, that was most strongly associated with innovation. Task reflexivity was an important predictor of innovation time 1, time 2). Only one measure of TMT diversity was associated with innovation - tenure diversity -in time 2 only. Organisational context played an important role in determining innovation. This was positively associated with innovation - but with one dimension of organisational learning only. The ability to share information (access to information) was not associated with innovation but the motivation to share information was (perceiving the sharing of information to be valuable). Innovative climate was also associated with innovation. This study suggests that this will lead to innovative outcomes if employees perceive the organisation to support risk, experimentation and other innovative behaviours.

But it’s not all about the sex:mothering, normalisation and young learning disabled people

This paper is about mothering, young learning disabled people, their sexualised and relationship lives and normalisation - not through the lens of the disabled person, but via a mothers perspective and theoretical discussion. As a mother who has a learning disabled daughter, a feminist and an academic, my own mothering experience, my PhD research and social theory are woven throughout this paper with the intention of opening up debate about sex, intimacy, normalisation, and how this impacts upon young learning disabled people. I suggest that the relationship between sex, reproduction, intimacy and intellectual impairment, and a project to decipher what it means to be human, in all its dirty glory are also part of the discourse that needs to be discussed experientially and theoretically. So much so that the messy world within which we all live can be variously and differently constructed.

Heritage and innovative learning approaches:an alternative approach to engineering education

Over recent years, the role of engineering in promoting a sustainable society has received much public attention [1] with particular emphasis given to the need to promote the future prosperity and security of society through the recruitment and education of more engineers [2,3]. From an employment perspective, the Leitch Review [4] suggested that ‘generic’ transferable employability skills development should constitute a more substantial part of university education. This paper argues that the global drivers impacting engineering education [5] correlate strongly to those underpinning the Leitch review, therefore the question of how to promote transferable employability skills within the wider engineering curriculum is increasingly relevant. By exploring the use of heritage in the engineering curriculum as a way to promote learning and engage students, a less familiar approach to study is discussed. This approach moves away from stereotypical notions of the use of information technology as representing the pinnacle of innovation in education. Taking the student experience as its starting point, the paper draws upon the findings of an exploratory study critically analysing the pedagogical value of using heritage in engineering education. It discusses a teaching approach in which engineering students are taken out of their ‘comfort zone’ - away from the classroom, laboratory and computer, to a heritage site some 100 miles away from the university. The primary learning objective underpinning this approach is to develop students’ transferable skills by encouraging them to consider how to apply theoretical concepts to a previously unexplored situation. By reflecting upon students’ perceptions of the value of this approach, and by identifying how heritage may be utilised as an innovative learning and teaching approach in engineering education, this paper makes a notable contribution to current pedagogical debates in the discipline.

Peer mentoring and experiential learning:the pathway to success

An analysis of the value of peer mentoring as an experiential learning approach

National system of innovation and technological learning:an integrated framework for understanding technological capability development in the Russian forestry sector

One of the issues in the innovation system literature is examination of technological learning strategies of laggard nations. Two distinct bodies of literature have contributed to our insight into forces driving learning and innovation, National Systems of Innovation (NSI) and technological learning literature. Although both literatures yield insights on catch-up strategies of 'latecomer' nations, the explanatory powers of each literature by itself is limited. In this paper, a possible way of linking the macro- and the micro-level approaches by incorporating enterprises as active learning entities into the learning and innovation system is proposed. The proposed model has been used to develop research hypotheses and indicate research directions and is relevant for investigating the learning strategies of firms in less technologically intensive industries outside East Asia.

Small business development and the “learning organisation”

The paper proffers a tentative conceptualisation of the “small business strategic learning process”, demonstrating the complexity of the small firm learning and management task. The framework, built upon personal construct theory and learning theories, is elaborated through the grounding of relevant areas of the strategic management literature in an understanding of the distinctive managerial and behavioural features of the small business. The framework is then utilised to underpin consideration of the concepts of “organisational learning” and the “learning organisation” within a small firm developmental context. It is suggested that whilst organisational learning may be a key and effective small business management approach to underpin sustainable development, the learning organisation, as currently conceived in the mainstream literature, fails to recognise and address the idiosyncrasies, problems and constraints relating to sustainable small business development. There does appear, however, to be great potential for extending understanding of the learning organisation concept into the small business context. An indicative research agenda is suggested.

Recent advances in fibre grating devices and their sensing applications

Over the last twenty years, we have been continuously seeing R&D efforts and activities in developing optical fibre grating devices and technologies and exploring their applications for telecommunications, optical signal processing and smart sensing, and recently for medical care and biophotonics. In addition, we have also witnessed successful commercialisation of these R&Ds, especially in the area of fibre Bragg grating (FBG) based distributed sensor network systems and technologies for engineering structure monitoring in industrial sectors such as oil, energy and civil engineering. Despite countless published reports and papers and commercial realisation, we are still seeing significant and novel research activities in this area. This invited paper will give an overview on recent advances in fibre grating devices and their sensing applications with a focus on novel fibre gratings and their functions and grating structures in speciality fibres. The most recent developments in (i) femtosecond inscription for microfluidic/grating devices, (2) tilted grating based novel polarisation devices and (3) dual-peak long-period grating based DNA hybridisation sensors will be discussed.

Exploring the relationships between network change and network learning

This paper relates the concept of network learning - learning by a group of organizations as a group - to change and notions of change management. Derived initially from a review of literature on organizational learning (OL) and interorganizational networks, and secondary cases of network learning, the concept was evaluated and developed through empirical investigation of five network learning episodes in the group of organizations that comprises the English prosthetics service. We argue that the notion of network learning enables a richer understanding of developments in networks over extended periods of time than can be afforded through more established concepts of change and change management alone.