Microresonators are devices that confine light in small volumes through total internal reflection. Introducing an emissive species into a microresonator allows for resonance enhanced emission at frequencies where the spectrum of the emissive species overlaps with the resonant frequencies of the microresonator. Previous research has led to a good understanding of these phenomena in 1D and 2D microresonators, but many 3D microresonator geometries have not yet been investigated. This work details the successful creation and demonstration of a cubic polymeric optical microresonator.

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This thesis presents a study of lasing properties and optical amplification in semiconducting conjugated polymers and dendrimers. Configured as surface-emitting distributed feedback lasers, the effect of incorporating wavelength-scale microstructure on the output of the devices is examined along with the ability to create such structures using simplified fabrication processes such as soft lithography. Conjugated materials have received a great deal of interest due to their broad spectral absorption, emission, ability to exhibit gain and ease of processing from solution. As a result, they show great potential for a variety of applications such as photovoltaics, displays, amplifiers and lasers. To date however, there has only been one demonstration of a polymer optical amplifier. A broadband, solution based polymer amplifier is presented where the gain overlaps with the transmission window of polymer optical fibres. The effect of transitions that reduce the availability of gain in conjugated polymers is also examined by studying saturation of absorption in thin films. Producing wavelength scale microstructure is traditionally a slow, expensive technique. Here, solvent assisted micromoulding is used to pattern polymer films in less than two minutes. The effect of the variations in the pattern transfer on the laser characteristics is examined. The micromoulding technique is then applied to fabricating novel device types such as circular gratings and flexible plastic lasers. Encapsulation of the micromoulded laser is then shown to improve the lifetime of the device by over three orders of magnitude. The degradation effects witnessed during this extended operation are characterised quantitatively, an area of study where little data exists in the literature. A novel class of branched dendrimer materials whose properties can be independently tuned due to their modular architecture are configured as blue-emitting distributed feedback lasers. The ability to tune the emission wavelength by varying the film thickness is demonstrated. By changing the chemical groups contained within the molecule, further tuning of the emission can be obtained along with the demonstration of a highly efficient blue-emitting dendrimer laser. Chemosensing using dendrimer lasers is presented by demonstrating the incredibly sensitive response of the laser device to trace vapours of nitro-benzene compounds. The future application of which could be highly beneficial in the detection of explosives.

>Magister Scientiae - MSc / Electrochemiluminescence (EeL) is applied for industrial applications that have considerable potential, such as clinical diagnostic, analytical chemistry, and light-emitting devices, due to selectivity, sensitivity for detection and quantification of molecules through generation of fluorescence light when electric current is applied on the materials. In EeL the electrochemical reaction allows for precise control over the time and position of the light emitting reaction. The control over time allows one to synchronise the luminescence and the biochemical reaction under study and control over position not only improves sensitivity of the instrument by increasing the signal to noise ratio, but also allows multiple analytical reactions in the same sample to be analyzed using an electrode array. The EeL generation fluorescent materials are based on inorganic semiconductor materials for light-emitting devices. Further progress in this EeL field mainly depends on discovery of new advanced materials, interfacial films and nanoparticle coatings, advances in microfluidics leading to total increase in EeL properties. There has been extensive use of polymers for enhancement of EeL properties. Electrochemiluminescent conjugated polymers constitute a new class of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials for the commercial market of light-emitting devices such as lightemitting diodes and polymer laser devices (PLDs).