School of Physics - Research Publications

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Author: Djalalian-Assl, Sead × Author: Prawer, Steven × End date: 2019 × Start date: 2010 ×

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    Filling schemes at submicron scale: Development of submicron sized plasmonic colour filters
    Rajasekharan, R ; Balaur, E ; Minovich, A ; Collins, S ; James, TD ; Djalalian-Assl, A ; Ganesan, K ; Tomljenovic-Hanic, S ; Kandasamy, S ; Skafidas, E ; Neshev, DN ; Mulvaney, P ; Roberts, A ; Prawer, S (NATURE PORTFOLIO, 2014-09-22)
    The pixel size imposes a fundamental limit on the amount of information that can be displayed or recorded on a sensor. Thus, there is strong motivation to reduce the pixel size down to the nanometre scale. Nanometre colour pixels cannot be fabricated by simply downscaling current pixels due to colour cross talk and diffraction caused by dyes or pigments used as colour filters. Colour filters based on plasmonic effects can overcome these difficulties. Although different plasmonic colour filters have been demonstrated at the micron scale, there have been no attempts so far to reduce the filter size to the submicron scale. Here, we present for the first time a submicron plasmonic colour filter design together with a new challenge - pixel boundary errors at the submicron scale. We present simple but powerful filling schemes to produce submicron colour filters, which are free from pixel boundary errors and colour cross- talk, are polarization independent and angle insensitive, and based on LCD compatible aluminium technology. These results lay the basis for the development of submicron pixels in displays, RGB-spatial light modulators, liquid crystal over silicon, Google glasses and pico-projectors.
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    Micro-concave waveguide antenna for high photon extraction from nitrogen vacancy centers in nanodiamond
    Rajasekharan, R ; Kewes, G ; Djalalian-Assl, A ; Ganesan, K ; Tomljenovic-Hanic, S ; McCallum, JC ; Roberts, A ; Benson, O ; Prawer, S (Nature Publishing Group: Open Access Journals - Option C, 2015-07-14)
    The negatively charged nitrogen-vacancy colour center (NV(-) center) in nanodiamond is an excellent single photon source due to its stable photon generation in ambient conditions, optically addressable nuclear spin state, high quantum yield and its availability in nanometer sized crystals. In order to make practical devices using nanodiamond, highly efficient and directional emission of single photons in well-defined modes, either collimated into free space or waveguides are essential. This is a Herculean task as the photoluminescence of the NV centers is associated with two orthogonal dipoles arranged in a plane perpendicular to the NV defect symmetry axis. Here, we report on a micro-concave waveguide antenna design, which can effectively direct single photons from any emitter into either free space or into waveguides in a narrow cone angle with more than 80% collection efficiency irrespective of the dipole orientation. The device also enhances the spontaneous emission rate which further increases the number of photons available for collection. The waveguide antenna has potential applications in quantum cryptography, quantum computation, spectroscopy and metrology.