Progress in multichannel all-optical regeneration based on fiber technology

Multiwavelength all-optical regeneration has the potential to substantially increase both the capacity and scalability of future optical networks. In this paper, we review recent promising developments in this area. First, we recall the basic principles of multichannel regeneration of high bit rate signals in optical communication systems before discussing the current technological approaches. We then describe in detail two fiber-based multichannel 2R regeneration techniques for return-to-zero-on-off keying based on 1) dispersion managed systems and 2) direction and polarization multiplexing. We present results illustrating the levels of performance so far achieved and discuss various practical issues and prospects for further performance enhancement.

Spin dependent photoconductivity in silicon-on-sapphire

Resonant and non resonant spin dependent photoconductivity is observed in(100) silicon films grown on sapphire by CVD and MBE techniques. The CVD films are either in their as-grown state or have undergone single or double solid phase epitaxial regrowth. For all samples, a resonant decrease in photoconductivity is observed at a field of about 0.34 T for a microwave frequency of about 9.7 GHz and at about 3.3 mT when the frequency is about 92 MHz. For all samples the maximum fractional change in photoconductivity is approximately 10-4 independent of magnetic field strength.

Polarization tailored novel vector beams based on conical refraction

Coherent vector beams with involved states of polarization (SOP) are widespread in the literature, having applications in laser processing, super-resolution imaging and particle trapping. We report novel vector beams obtained by transforming a Gaussian beam passing through a biaxial crystal, by means of the conical refraction phenomenon. We analyze both experimentally and theoretically the SOP of the different vector beams generated and demonstrate that the SOP of the input beam can be used to control both the shape and the SOP of the transformed beam. We also identify polarization singularities of such beams for the first time and demonstrate their control by the SOP of the input beam.

Amplitude response of a unilaterally constrained nonlinear micromechanical resonator

Dynamical systems that involve impacts frequently arise in engineering. This Letter reports a study of such a system at microscale that consists of a nonlinear resonator operating with an unilateral impact. The microresonators were fabricated on silicon-on-insulator wafers by using a one-mask process and then characterised by using the capacitively driving and sensing method. Numerical results concerning the dynamics of this vibro-impact system were verified by the experiments. Bifurcation analysis was used to provide a qualitative scenario of the system steady-state solutions as a function of both the amplitude and the frequency of the external driving sinusoidal voltage. The results show that the amplitude of resonant peak is levelled off owing to the impact effect and that the bandwidth of impacting is dependent upon the nonlinearity and the operating conditions.

H-induced platelet and crack formation in hydrogenated epitaxial Si/Si0.98 B0.02 /Si structures

An approach to transfer a high-quality Si layer for the fabrication of silicon-on-insulator wafers has been proposed based on the investigation of platelet and crack formation in hydrogenated epitaxialSi/Si0.98B0.02/Si structures grown by molecular-beam epitaxy. H-related defect formation during hydrogenation was found to be very sensitive to the thickness of the buried Si0.98B0.02 layer. For hydrogenated Si containing a 130nm thick Si0.98B0.02 layer, no platelets or cracking were observed in the B-doped region. Upon reducing the thickness of the buried Si0.98B0.02 layer to 3nm, localized continuous cracking was observed along the interface between the Si and the B-doped layers. In the latter case, the strains at the interface are believed to facilitate the (100)-oriented platelet formation and (100)-oriented crack propagation.

Counting on use of technology to enhance learning

In global policy documents, the language of Technology-Enhanced Learning (TEL) now firmly structures a perception of educational technology which ‘subsumes’ terms like Networked Learning and e-Learning. Embedded in these three words though is a deterministic, economic assumption that technology has now enhanced learning, and will continue to do so. In a market-driven, capitalist society this is a ‘trouble free’, economically focused discourse which suggests there is no need for further debate about what the use of technology achieves in learning. Yet this raises a problem too: if technology achieves goals for human beings, then in education we are now simply counting on ‘use of technology’ to enhance learning. This closes the door on a necessary and ongoing critical pedagogical conversation that reminds us it is people that design learning, not technology. Furthermore, such discourse provides a vehicle for those with either strong hierarchical, or neoliberal agendas to make simplified claims politically, in the name of technology. This chapter is a reflection on our use of language in the educational technology community through a corpus-based Critical Discourse Analysis (CDA). In analytical examples that are ‘loaded’ with economic expectation, we can notice how the policy discourse of TEL narrows conversational space for learning so that people may struggle to recognise their own subjective being in this language. Through the lens of Lieras’s externality, desubjectivisation and closure (Lieras, 1996) we might examine possible effects of this discourse and seek a more emancipatory approach. A return to discussing Networked Learning is suggested, as a first step towards a more multi-directional conversation than TEL, that acknowledges the interrelatedness of technology, language and learning in people’s practice. Secondly, a reconsideration of how we write policy for educational technology is recommended, with a critical focus on how people learn, rather than on what technology is assumed to enhance.

International technology transfer:perceptions and reality of quality and reliability

Impressions about product quality and reliability can depend as much on perceptions about brands and country of origin as on data regarding performance and failure. This has implications for companies in developing countries that need to compete with importers. For manufacturers in industrialised countries it has implications for the value of transferred technologies. This article considers the issue of quality and reliability when technology is transferred between countries with different levels of development. It is based on UK and Chinese company case studies and questionnaire surveys undertaken among three company groups: UK manufacturers; Chinese manufacturers; Chinese users. Results show that all three groups recognise quality and reliability as important and support the premise that foreign technology based machines made in China carry a price premium over Chinese machines based on local technology. Closer examination reveals a number of important differences concerning the perceptions and reality of quality and reliability between the groups.

RFID technology to support environmentally sustainable supply chain management

RFID is one of the contemporary technologies that has the potential to enable improved data gathering and cross-companies integration, and thus achieve cost efficiency. However, RFID has not yet become primary approach to collect data from the supply chain activities. This is partly due to (relative) high cost of implementation, partly due to technical deficiencies, as well as cross-company systems integration issues. This paper discusses a potential application area for RFID technology, which is environmentally sustainable supply chain management. The paper discusses the current practices in green supply chain management, and proposes possible applications of RFID enabling green supply chain management. The paper also proposes an idea of ad hoc RFID systems which are rapidly deployable and require minimal, if at all, pre-existing infrastructure. © 2010 IEEE.

Optimizing supply chain waste management through the use of RFID technology

This paper presents a Decision Support System framework based on Constrain Logic Programming and offers suggestions for using RFID technology to improve several of the critical procedures involved. This paper suggests that a widely distributed and semi-structured network of waste producing and waste collecting/processing enterprises can improve their planning both by the proposed Decision Support System, but also by implementing RFID technology to update and validate information in a continuous manner. © 2010 IEEE.

Manufacturing technology sourcing practices in the USA

Some companies are heavily reliant on the capabilities of their manufacturing technology for product competitiveness. Likewise, the capabilities of a manufacturing technology are dependent on the sourcing policy that the host company practices. This paper describes research that has explored a wide variety of US companies to understand manufacturing technology sourcing policies and how they have been formed. This research finds that there is a preference amongst the US organizations studied not to become involved with equipment manufacture, though some examples of full integration do occur. These policies are not determined by formalized decision processes, rather they are formed implicitly during technology choice. In this research, factors that influence a technology source have been identified. These drivers are then used to establish a methodology that will help practising managers to form a technology sourcing decision. This methodology takes into account the business demands placed on a technology, along with the characteristics of the host company's supplier base.

An investigation into the adoption of electronic business in Saudi Arabia using technology-organisation-environment framework

Despite the proliferation of e-business adoption by organisations and the world-wide growth of the e-business phenomenon, there is a paucity of empirical studies that examine the adoption of e-business in the Middle East. The aim of our study is to provide insights into the salient e-business adoption issues by focusing on Saudi Arabian businesses. We developed a conceptual model for electronic business (e-business) adoption incorporating ten factors based on the technology-organization-environment framework. Survey data from 550 businesses were used to test the model and hypotheses. We conducted confirmatory factor analysis to assess the reliability and validity of constructs. The findings of the study suggest that firm technology competence, size, top management Support, technology orientation, consumer readiness, trading partner readiness and regulatory support are important antecedents of e-business adoption and utilisation. In addition, the study finds that, competitive pressure and organisational customer and competitor orientation is not a predictor for e-business adoption and utilisation. The implications of the findings are discussed and suggestions for future inquiry are presented.

Superfocusing of high-M2 semiconductor laser beams:experimental demonstration

The focusing of multimode laser diode beams is probably the most significant problem that hinders the expansion of the high-power semiconductor lasers in many spatially-demanding applications. Generally, the 'quality' of laser beams is characterized by so-called 'beam propagation parameter' M2, which is defined as the ratio of the divergence of the laser beam to that of a diffraction-limited counterpart. Therefore, M2 determines the ratio of the beam focal-spot size to that of the 'ideal' Gaussian beam focused by the same optical system. Typically, M2 takes the value of 20-50 for high-power broad-stripe laser diodes thus making the focal-spot 1-2 orders of magnitude larger than the diffraction limit. The idea of 'superfocusing' for high-M2 beams relies on a technique developed for the generation of Bessel beams from laser diodes using a cone-shaped lens (axicon). With traditional focusing of multimode radiation, different curvatures of the wavefronts of the various constituent modes lead to a shift of their focal points along the optical axis that in turn implies larger focal-spot sizes with correspondingly increased values of M2. In contrast, the generation of a Bessel-type beam with an axicon relies on 'self-interference' of each mode thus eliminating the underlying reason for an increase in the focal-spot size. For an experimental demonstration of the proposed technique, we used a fiber-coupled laser diode with M2 below 20 and an emission wavelength in ~1μm range. Utilization of the axicons with apex angle of 140deg, made by direct laser writing on a fiber tip, enabled the demonstration of an order of magnitude decrease of the focal-spot size compared to that achievable using an 'ideal' lens of unity numerical aperture. © 2014 SPIE.

Market-level information and the diffusion of competing technologies:an exploratory analysis of the LAN industry

Market-level information diffused by print media may contribute to the legitimation of an emerging technology and thus influence the diffusion of competing technological standards. After analyzing more than 10,000 trade media abstracts from the Local Area Networks (LAN) industry published between 1981 and 2000, we found the presence of differential effects on the adoption of competing standards by two market-level information types: technology and product availability. The significance of these effects depends on the technology's order of entry and suggests that high-tech product managers should make strategic use of market-level information by appropriately focusing the content of their communications. © 2007 Elsevier B.V. All rights reserved.

The post-adoption phase of the broadband in small businesses

In spite of the increasing significance of broadband, many small and medium enterprises (SMEs) are unaware of or unappreciative of its benefits. This is potentially a problem for governments, Internet Service Providers and other supply side institutions. The current study empirically verifies applicability of an extended IS continuance model controlling for organizational variables based on the Technology-Organization-Environment framework to examine factors influencing broadband post-adoption behavior of SMEs in Singapore. Strong support for the model has been manifested by the results, providing insight into influential factors. Results of the study suggest that perceived usefulness is a strong predictor of users’ continuance intention, followed by satisfaction with broadband usage as a significant but weaker predictor. SMEs in a more competitive business environment and whose key executive possesses greater IT knowledge are more likely to use broadband.