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Abstract:

In this paper, we describe a series of improvements that have been made to our direct laser writing waveguide/microfluidic fabrication technology. We demonstrate significant increases in the writing speed (measured in micrometres of written structure per second) by both the use of customized photopolymers containing light emitting polymer and the inclusion of a diffractive optical element to enable the writing of multiple channels in a single pass. © 2008 IOP Publishing Ltd.

Abstract:

We present the highlights of a research programme on hybrid inorganic-organic light emitters. These devices combine recent developments in III-V nitride technology (including UV emitting micro-arrays and specifically tailored quantum wells) with conjugated polymers to access the entire visible spectrum. Two types of devices are studied, those based on down conversion of the quantum well emission by radiative transfer and those based on non-radiative resonant energy transfer. The spectral and operating characteristics of the devices are described in detail. Selectable colour micro-arrays and bar emitters are demonstrated. The nature of the non-radiative energy transfer process has also been studied and we find transfer efficiencies of up to 43% at 15 K, with a 1/R² dependence on the distance between quantum well and polymer layer, suggesting a plane-plane interaction. The relative importance of the non-radiative resonant energy transfer process increases with temperature to be up to 20 times more efficient, at 300 K, than the radiative transfer process. © 2008 IOP Publishing Ltd.

Abstract:

We report for the first time a UV curable polymer with effective optical transmission below 300 nm. Through careful control of kinetics, various viscosities can be generated to optimize the film forming properties via spin coating. The transmission of the monomers and films is investigated over a spectral range which spans the 240-370 nm output of ultraviolet AlInGaN light-emitting diodes. The refractive index of the polymer has been measured by ellipsometry to give a value of 1.57 at 280 nm. Using standard lithography techniques with reactive ion etching, arrays of microlenses have been fabricated in this polymer with diameters of 30 νm and below and are characterized by atomic force microscopy and confocal microscopy. © 2008 IOP Publishing Ltd.

Abstract:

We report the integration of micro-patterned polyfluorene conjugated polymers onto GaN-based ultraviolet (UV) micro-pixellated light-emitting diode arrays (micro-LEDs). The 64 × 64 element matrix-addressable AlInGaN devices have a pixel size of 20 νm diameter on a 50 νm pitch, emitting at 368 nm. Each array is covered with a 2.5 νm thick photo-curable deep-UV-transparent polymer and a 30 nm thick polyfluorene film. This polymer bi-layer is subsequently patterned into an array of 28 νm diameter discs aligned with the pixels of the micro-LED array. Polymer down-converted visible emission from these pattern-programmable organic/inorganic electroluminescent micro-arrays is achieved. © 2008 IOP Publishing Ltd.