Ashley D. Lloyd

Anomalous Optical Freedericksz Transition in an Absorbing Liquid Crystal

Abstract Laser-induced reorientation was studied in absorbing nematic films. The optical Freedericksz threshold occured at an intensity level of 50 W/cm2 in contrast to the normally observed few KW/cm2 value for transparent layers. Thermomechanical coupling is considered as a possible explanation of the observed anomaly.

Learning to use new technologies by older adults: Perceived difficulties, experimentation behaviour and usability

This paper examines the factors and theoretical frameworks for the adoption of technology for older adults, and proposes two models of technology acceptance and rejection, one from an ease of learning perspective, and one from a system and user perspective. Both models are supported from reports on two case studies of older adults using handheld touchscreen tablet devices; one in which the participants are supported during tasks primarily related to walking and navigation, and one in which participants are unsupported in communication related tasks. The first study shows the powerful role that facilitating conditions have for learning how to use digital technologies for this user group, whether supporting through step by step guidance, providing a friendly space to use trial and error methods, and/or provision of a manual. The second study shows the pitfalls of a lack of facilitating conditions during initial use, and highlights potential for appropriate design in helping to avoid some user errors during this phase.

Low-Power Optical Reorientation in Dyed Nematics

Abstract The optical reorientation process in nematic guest-host mixtures is investigated. It is found that for certain dyes the optical Freedericksz threshold is two orders of magnitude lower as in the pure host. The observations can be interpreted in terms of an enhanced optical torque which increases with the dye concentration.

The saturation limit to picosecond, induced absorption in dyes

Abstract The increase in transmission coefficient at high fluences, following low-fluence reverse saturable absorption (induced absorption), is demonstrated for the tricarbocyanine dye, HITCI. This novel effect is explained in terms of a modified three-level model of the singlet states. The absorption cross-section at 532 nm of the first excited state is determined to be 4.8x10-16 cm2, 29 times that of the ground state. We find the lifetime of the first excited state to be 1.5 ns and that of the second excited state to be of the order of 8 ps.

Theory of optical bistability in metal mirrored fabry-perot cavities containing thermo-optic materials

Abstract We present and analyse a new method for achieving all-optical bistability, in metal mirrored Fabry-Perot cavities containing thermo-optic material. It is shown how “butterfly” bistability is achieved in metal/metal mirrored cavities. Optimisation for low switching powers is considered for a dielectric/metal mirrored cavity. The use of nematic liquid crystals with such a system makes submilliwatt switching powers easily achievable.

Proven methods for innovation management: an executive wish list

Innovation specialists from the largest British companies discussed what they wanted to know about innovation, and asked the academic community to suggest some answers. Some, but by no means all, of their questions had already been answered in the published literature. The behaviours that support a culture of innovation include a market orientation, an innovation-friendly ruling coalition, and organisational structures that propel novelty. These behaviours also encourage creativity if the risk-taking employees are rewarded for success and if they are asked to explain their personal mission at intervals. Several methods which researchers have found effective for the identification of ideas which may become market winners are discussed, as are methods building organisational competencies for innovation. Some of their remaining questions are being addressed by research projects currently in progress.

All-optical bistability in nematic liquid crystals at 20 μW power levels

Optical switches at power levels as low as 14 μW, allowing bistable operation with compact disk laser systems, are reported in optimized cavities containing planar‐aligned nematic liquid crystals.

Optical Bistable Devices for Memory and Logic

Nonlinear interference filters and liquid crystal cells for low power optical bistability are reviewed. The use of filters for prototype optical circuitry and a proposed cellular-logic-image-processing architecture are described

Intercontinental Grids: An Infrastructure for Demand-Driven Innovation

This paper charts the evolution of an intercontinental Grid—INWA—from its first operation connecting Australia and Scotland; its subsequent extension to China; and its use to demonstrate the first large-scale research and education network for the Asia-Pacific region. The paper focuses on the gap between e-Science and e-Social Science arguing that the Grid topology is more compatible with the socio-legal demands of large-scale study of society than more dynamically distributed approaches, such as Cloud Computing. Foundational texts on Grid Computing and its appropriation by research programmes in the UK, USA and China have helped create a positive, symbolic value for Grid Computing. For INWA, this value helped when communicating the aims of the project to potential collaborators and so created the conditions for high-quality, socio-economic data to be placed in a collaborative, analytical environment. There is no equivalent symbolic value for Cloud Computing with potential consequences for its usefulness in establishing such collaborations in future.

Design and modeling of asymmetric Fabry-Perot electrooptic modulators containing a polymeric film

Asymmetric Fabry-Perot modulators containing an electrooptic polymeric film are described. The designs of these structures are optimized for reflection operation by maximizing both cavity finesse and the effective field strength acting across the spacer region, hence minimizing drive voltages. The electrooptic responses of these devices are modeled and the voltages required to realise 3-dB and 10-dB modulation are calculated. It is thus demonstrated that organic thin-film-based Fabry-Perot devices are potential candidates for high-speed, low-drive-voltage, electrooptic switches, modulators, and interconnect elements. Experimental results from prototype devices are also presented. >