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Browsing by Author "Forbes, A"

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  • Mafu, M; Dudley, Angela L; Goyal, S; Giovannini, D; McLaren, M; Padgett, MJ; Konrad, T; Petruccione, F; Lutkenhaus, N; Forbes, A (American Physical Society, 2013-09)
    We present an experimental study of higher-dimensional quantum key distribution protocols based on mutually unbiased bases, implemented by means of photons carrying orbital angular momentum. We perform (d + 1) mutually ...
  • Ismail, Y; Barnes, G; Mhlanga, T; Belyi, V; Forbes, A (SPIE, 2010-08)
    As in the case of zero-order Bessel beam being produced by illuminating an axicon with a Gaussian beam, higher-order Bessel beams are generated by substituting the Gaussian beam with a Laguerre Gaussian (LG) beam. These ...
  • Rosales-Guzman, C; Trichili, A; Dudley, Angela; Ndagano, B; Salem, AB; Zghal, Mourad; Forbes, A (SPIE, 2016-09)
    Current optical communication technologies are predicted to face a bandwidth capacity limit in the near future. The nature of the limitation is fundamental rather than technological and is set by nonlinearities in optical ...
  • Burger, L; Litvin, I; Ngcobo, S; Forbes, A (SPIE, 2014-03)
    The beam from a laser resonator is determined by the optical elements it contains. Most commonly, these consist of two spherical mirrors, but phase- and amplitude-modulating elements can also be included to produce custom ...
  • Litvin, IA; Forbes, A (International Society for Optical Engineering (SPIE), 2007)
    The authors investigate the phase conjugating element of a two element Fourier transform beam shaping scheme and the impact this element has on the resulting propagation. It is shown that there are stricter limitations ...
  • Dudley, Angela L; Majola, N; Chetty, N; Forbes, A (American Association of Physics Teachers, 2016-02)
    The coherent superposition of a Gaussian beam with an optical vortex can be mathematically described to occupy the complex plane. The authors provide a simple analogy between the mathematics, in the form of the complex ...
  • Goyal, SK; Roux, FS; Forbes, A; Konrad, T (American Physical Society, 2013-06)
    We present an implementation scheme for a quantum walk in the orbital angular momentum space of a laser beam. The scheme makes use of a ring interferometer, containing a quarter-wave plate and a q plate. This setup enables ...
  • Von Bergmann, H; Forbes, A; Roberts, T; Botha, L (The International Society for Optical Engineering, 2007)
    In this paper the author’s present results on the influence of acoustic waves on the output laser beam from high repetition rate TEA CO2 lasers. The authors show that acoustic waves generated inside the cavity lead to ...
  • Mthunzi, P; Forbes, A; Hawkins, D; Abrahamse, H; Karsten, AE (The International Society for Optical Engineering, 2005)
    A variety of strategies have been utilised for prevention and treatment of chronic wounds such as leg ulcers, diabetic foot ulcers and pressure sores1. Low Level Laser Therapy (LLLT) has been reported to be an invaluable ...
  • Mthunzi, P; Forbes, A; Hawkins, D; Abrahamse, H; Karsten, AE (2006-07)
    A variety of strategies have been utilised for prevention and treatment of chronic wounds such as leg ulcers, diabetic foot ulcers and pressure sores. Low Level Laser Therapy (LLLT) has been reported to be an invaluable ...
  • Forbes, A; Botha, L; Du Preez, N; Drake, T (The International Society for Optical Engineering, 2007)
    Laser ultrasonics is currently the optimal method for non-destructive testing of composite materials in the aerospace industry. The process is based on a laser-generated ultrasound wave which propagates inside the composite. ...
  • Naidoo, Darryl; Forbes, A; Aït-Ameur, K; Fromager, M (SPIE, 2011-01)
    A method of decomposing a dual-directional laser beam into a forward propagating field and a backward propagating field for an apertured plano-concave cavity is presented. An intra-cavity aperture is a simple method of ...
  • Ngcobo, S; Ait-Ameur, K; Forbes, A (2012-08)
    This work deals with the generation of symmetrical high order Laguerre Gaussian modes. These high order Laguerre-Gaussian beams are generated by forcing the laser using an annular binary Diffractive Optical Element whose ...
  • Naidoo, Darryl; Aït-Ameur, K; Brunel, M; Forbes, A (Springer Verlag, 2012)
    In this paper we demonstrate experimentally the intra-cavity generation of a coherent superposition of Laguerre–Gaussian modes of zero radial order but opposite azimuthal order. The superposition is created with a simple ...
  • Naidoo, Darryl; Litvin, I; Laskin, A; Forbes, A (SPIE Proceedings, 2014-02)
    We explore an intra-cavity beam shaping approach to generate a Gaussian distribution by the metamorphosis of a Gaussian beam into a flat-top distribution on opposing mirrors. The concept is tested external to the cavity ...
  • Naidoo, Darryl; Aït-Ameur, K; Forbes, A (SPIE, 2011-08)
    In this paper the authors explore vortex beams and in particular the generation of single LG0l modes and superpositions thereof. Vortex beams carry orbital angular momentum (OAM) and this intrinsic property makes them ...
  • Litvin, IA; Khilo, NA; Forbes, A; Belyi, VN (Society of Photo-Optical Instrumentation Engineers, 2009-08)
    In this paper the researchers report on two resonator systems for producing LDBLBs with arbitrary initial parameters. First resonator system is based on doublet of divergence and convergence lenses with spherical aberration. ...
  • Litvin, IA; Loveday, PW; Long, CS; Kazak, NS; Belyi, V; Forbes, A (Society of Photo-Optical Instrumentation Engineers (SPIE), 2008-08)
    There are many applications in which a laser beam with a flat–top intensity profile would be ideal, as compared to a laser beam with a non–uniform energy distribution. Standard stable optical resonators will unfortunately ...
  • Litvin, IA; Forbes, A (Society of Photo-Optical Instrumentation Engineers, 2009-08)
    In this paper the authors present the analytical and numerical analyses of two new resonator systems for generating flat–top–like beams. Both approaches lead to closed form expressions for the required cavity optics, but ...
  • Litvin, IA; Khilo, NA; Forbes, A; Belyi, VN (Optical Society of America, 2010-02)
    The authors report on two resonator systems for producing Bessel–like beams with longitudinally dependent cone angles (LDBLBs). Such beams have extended propagation distances as compared to conventional Bessel– Gauss beams, ...