Total technology practice : preliminary study for application in New Zealand schools : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Technology, at Massey University

The purpose of this research was to identify the important generic elements of total technology practice and to develop a preliminary list of the important techniques, knowledge and actions used by technologists. The research was based on the hypothesis that in technology education in New Zealand schools, the important elements of technology practice could be represented in the form of a model that could be used to organise and communicate the elements and knowledge involved in total technology practice. The research was undertaken with technologists working at Massey University and teachers involved in teaching technology. A product development research methodology was used to test ideas and develop a model of technology practice for use in New Zealand schools. The first phase of the research used the experience and knowledge of product development technologists to identify the important elements of technology practice and develop preliminary lists of techniques and knowledge involved in each element. A group of specialist technologists were used to verify these elements and identify detailed content. This research showed that total technology practice can be structured using seven elements that together provide a simplified description of total technology practice. The elements of practice associated with the human context and goal of technology practice were identified as society, the work environment, and purposeful action. The elements technologists bring to the context were organisation, information, resource use, and an extensive knowledge of techniques and the skill, ingenuity and experience to apply and adapt techniques to specific contexts and problems. Individual technologists were interviewed to identify the important practices and knowledge within their area of expertise. Technological knowledge was structured into a framework that reflected the way technologists broke complex systems into subsystems to solve problems and develop solutions. The detailed model developed with the technologists was evaluated by groups of teachers using focus group techniques and a small survey. The study indicated teachers perceived the model as a useful tool for communicating knowledge and understanding of technology practice and for structuring teaching units in technology education. This preliminary study indicated technology practice can be described in terms of seven elements and communicated in the form of a model. Technologists organise their knowledge into structures that facilitate application in practice. This structure and much of its knowledge can be made explicit and used to help students understand technological products and develop capability in their technology practice. This study has identified a structure for technology practice and technological knowledge that is common to all seven technological areas and nine contexts identified in the New Zealand technology curriculum

Lateral groove geometry for planar UV written evanescent devices - new flexibility new devices

Conventional evanescent optical devices have made use of etched windows to allow access of an optical field to a material of interest. Such devices are a route to accurate refractive index sensors and to realising modulators, however, the geometry of etching the cladding to give the fluid access to a pre-defined core waveguide mode is limiting. In this work, we present an alternative approach in which a groove is cut using a polishing saw blade to give a vertical, high optical quality trench. Optical waveguides are then UV written to allow evanescent lateral access of the mode to a fluid placed in the trench. This seemingly subtle change in geometry provides greatly increased flexibility to tailor the interaction between the optical mode and the surrounding material, by, for example, changing the mode size and the allowing couplers or tapers to be used

Fabrication of a single mode laser by UV-writing in neodymium doped silica-on-silicon

We describe the fabrication of a waveguide laser by UV-writing in neodymium doped silica-on-silicon. The substrate is fabricated by Flame Hydrolysis Deposition and solution doping techniques. Lasing at 1048-1056nm was observed with a slope efficiency of 33% and threshold of 4mW for the transition. Lasing was also observed at 1356nm

Nonlinear ptychographic coherent diffractive imaging

Ptychographic Coherent diffractive imaging (PCDI) is a significant advance in imaging allowing the measurement of the full electric field at a sample without use of any imaging optics. So far it has been confined solely to imaging of linear optical responses. In this paper we show that because of the coherence-preserving nature of nonlinear optical interactions, PCDI can be generalised to nonlinear optical imaging. We demonstrate second harmonic generation PCDI, directly revealing phase information about the nonlinear coefficients, and showing the general applicability of PCDI to nonlinear interactions

Gouy phase compensation in quasi-phase matching

In any focussed nonlinear interaction the focus induced phase shift, known as the Gouy phase shift, provides an imperfection in phase matching for any linearly invariant material. However, using an appropriately designed quasi-phase matched structure it is theoretically possible to compensate for the deleterious effects of the Gouy phase shift, allowing a symmetric frequency response and tighter optimal focussing than in a uniform material

Direct optical observation of walls and disclination effects in active photonic devices

Liquid crystal tunable Bragg Gratings defined in planar substrates via a laser patterning technique exhibit complex wavelength tuning. This tuning displays threshold points and hysteresis. These tuning features are shown to be a manifestation of physical processes occurring in the confined geometry of our tunable devices. Such physical processes include the formation and removal of line disclinations and an associated wall. We discuss the effect of walls in the liquid crystal with regards to voltage tuning characteristics and whether they may allow faster wavelength tuning

Flat fiber: the flexible format for distributed lab-on-a-chip

Integrated optical devices offer dense, multifunctional capability in a single robust package but are rarely considered compatible with the fields of remote or distributed sensing or long-haul 'one-dimensional' fibers. Here we aim to change that by introducing a 'flat-fiber' process that combines the advantages of existing low-cost fiber drawing with the functionality of planar lightwave circuits in a novel hybrid format. By taking this approach, we hope to extend beyond the limitations of traditional planar and fiber substrates - allowing exotic material compositions, device layouts, and local sensing functions to be distributed over extended distances with no coupling or compatibility concerns in highly functional distributed lab-on-a-chip devices

Flat-top temperature tuning response in periodically-poled nonlinear crystals

Second harmonic generation via periodically-poled nonlinear materials offers an efficient means of generating high-quality visible light that would be otherwise unattainable with traditional laser sources. While this technology has the potential for implementation in many mass-industrial applications, temperature stability requirements of 0.1 deg.C can make packaging with a pump source problematic. Using our high fidelity poling technique we have achieved precise placement of poled domains in Lithium Niobate based on the resulting mathematical models. These initial devices provide more than 4 deg.C flat-top temperature stability, albeit with a corresponding loss in operational efficiency. Our aim is to implement improved designs in magnesium-doped Lithium Niobate for packaging with near-room temperature diode-based pump sources, as could be applied towards RGB TV and projector applications

New geometry for planar UV written refractive index sensors

We shall present some of our recent results from our work on UV written planar waveguide refractive index sensors. Refractive index of an analyte is measured through the perturbation of an optical mode, interrogation of the modal index is achieved via the reflected spectra from a Bragg grating defined in the same process as the channel waveguide. Here we introduce a new geometry which embraces the benefits of planar technology to realise new integrated devices. The geometry allows several different sensors to be defined on the same substrate each offering complementary information. Such information may include index as a function of penetration depth for surface binding analytes, interrogation wavelength for dispersion analysis, enhanced sensitivity in specific index ranges and temperature compensation. We shall also outline the inherent fabrication advantages and device feature benefits, including a reduction in return loss, spectral artefacts and a suggested reduction in stress induced birefringence. The silica sensing surface opposed to gold used in SPR devices opens new avenues to exploit surface binding. With a marked reduction in complexity and cost these devices may have significant impact in future sensor markets

Green-pumped, picosecond MgO:PPLN optical parametric oscillator

We investigate the performance of a magnesium-oxide-doped periodically poled lithium niobate crystal (MgO:PPLN) in an optical parametric oscillator (OPO) synchronously-pumped by 530nm, 20ps, 230MHz pulses with an average power of up to 2W from a frequency-doubled, gain-switched laser diode seed and a multi-stage Yb:fiber amplifier system. The OPO produces ~165mW (signal, 845nm) and ~107mW (idler, 1421nm) of average power for ~1W of pump power and can be tuned from ~800nm to 900nm (signal) and 1.28µm to 1.54µm (idler). Observations of photo-refraction and green-induced infrared absorption (GRIIRA) in different operational regimes of the MgO:PPLN OPO are described and the role of peak intensity and average power are investigated, both with the aim to find the optimal operating regime for pulsed systems