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Three candidates for micro- to nano-scale light sources for application in various forms of scanning probe optical microscopy are investigated and optimised. These are sharp gold tips, nano-apertures in patterned silver films and light emitting metal-insulator-metal tunnel junctions. A safe fabrication method was developed and optimised for making sharp « 25 nm end radius), symmetric Au tips for use in light emission in ambient scanning tunnelling microscopy. The Au tips were produced using a 2-step etching process in an electrolyte comprising a 20% CaCh solution. High resolution in both topography and photon mapping . was achieved using these Au tips. Surface plasmon polaritons (SPPs), selectively excited in attenuated total reflection (ATR) with an incident annular laser beam, formed with a novel conic input optics set-up, enhances the optical transmission through a sub-wavelength aperture in a silver film. The use ofan ion beam milled, circular grating pattern on the output face ofthe silver film, concentric with the aperture, gave a further enhancement by a factor of 5 and a total enhancement by a factor up to 40 relative to the off-resonance transmission through an identical sub-wavelength aperture in a smooth metal film. Micro-scale light emitting tunnel junctions (LETJs) were fabricated capable ofwithstanding an applied bias ofup to 4V. LETJs with small dimensions (on the scale ofthe fast mode SPP propagation length) have a greater overall quantum efficiency that those of larger dimension junctions and reduce the gap in photon emission efficiency between the high (>2.5 eV) and low energy «2.5 eV) regimes. Both features are explained in terms ofthe proportion offast mode SPPs that can propagate to, and scatter from the edges ofthese otherwise smooth devices.

An integrated experimental setup for proposed work involving laser collimation of a gallium atomic beam has been designed and constructed. Laser cooling transitions in this Group Thirteen element are accessed using commercial blue/violet diode lasers at 403 and 417nm ep1J2 - 2S1/2 and 2P312 - 2S1/2 transitions respectively). For the purpose of laser frequency stabilization, hyperfine-resolved spectra at these wavelengths have been obtained using saturated absorption spectroscopy in a commercial see-through Ga-Ne hollow cathode discharge lamp. A wavelength modulation technique is used to obtain high quality spectra in the presence of severe velocity-changing collisions which render standard amplitude modulation techniques almost completely ineffective. Preliminary locking results using third derivative Iineshapes are reported. In addition, in order to fully study the influence of velocity-changing collisions for various Ga-rare gas combinations, a home-built hollow cathode lamp has been constructed. Resistively-heated home-built and commercial gallium atomic beam sources (required operating temperature -1200°C) have been investigated. Hyperfine transitions at 403 and 417nm have been probed using absorption spectroscopy in a mechanically-collimated atomic beam generated using the home-built source. T.he five laser frequencies necessary to create a closed set of laser cooling transitions involving a large proportion of ground state atoms are derived from the two source lasers using an electro-optic (at 403nm) and acousto-optic (at 417nm) modulators. Possibilities for a full optical setup incorporating generation and recombination of frequency-stabilized cooling beams are briefly discussed, as are the prospects for future atomic beam collimation experiments.

No description available.

No description available.

No description available.

No description available.

No description available.