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Browsing by Author "Ngcobo, Sandile"

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Digital control of laser modes with an intra-cavity spatial light modulator

Author: Ngcobo, Sandile ; Litvin, I ; Burger, L ; Forbes, A Date: Feb 2014 In this paper we outline a simple laser cavity which produces customised on-demand digitally controlled laser modes by replacing the end-mirror of the cavity with an electrically addressed reflective phase-only spatial light modulator as a ... Read more
Digital laser for on-demand intracavity selective excitation of second harmonic higher-order modes

Author: Bell, Lebohang T ; Kgomo, Mosima B ; Ngcobo, Sandile Date: May 2020 In this article, we demonstrate selective excitation of second harmonic higher-order modes inside a diode end-pumped solid-state laser resonator that comprises of a nonlinear potassium titanyl phosphate (KTP) crystal and a digitally addressed ... Read more
A digital laser for on-demand laser modes

Author: Ngcobo, Sandile ; Litvin, I ; Burger, L ; Forbes, A Date: Aug 2013 Customizing the output beam shape from a laser invariably involves specialized optical elements in the form of apertures, diffractive optics and free-form mirrors. Such optics require considerable design and fabrication effort and suffer from ... Read more
Digital laser mode amplification using ND: YAG amplifier

Author: Bell, Teboho ; Ngcobo, Sandile Date: Jul 2016 In this paper we demonstrate the output power amplification of the generated higher-order modes from a digital laser by using an extra-cavity Nd: YAG amplifier. Read more
The digital laser: on-demand laser modes with the click of a button

Author: Forbes, A ; Ngcobo, Sandile ; Burger, L ; Litvin, IA Date: Feb 2014 In this paper we will outline our recent advances in all-digital control of light. Importantly, we will outline how to create a so-called “digital laser”, where a conventional laser mirror is replaced with a phase-only spatial light modulator. ... Read more
Discrete excitation of mode pulses using a diode-pumped solid-state digital laser

Author: Ngcobo, Sandile ; Bell, Teboho Date: Feb 2016 In this paper, we experimentally demonstrate novel method of generating discrete excitation of on-demand Lagaurre-Gaussian (LG) mode pulses, in a diode pumped solid-state digital laser. The digital laser comprises of an intra-cavity spatial ... Read more
Doughnut laser beam as an incoherent superposition of two petal beams

Author: Litvin, IA ; Ngcobo, Sandile ; Naidoo, Darryl ; Ait-Ameur, K ; Forbes, A Date: Feb 2014 Laguerre–Gaussian beams with a nonzero azimuthal index are known to carry orbital angular momentum (OAM), and are routinely created external to laser cavities. The few reports of obtaining such beams from laser cavities suffer from inconclusive ... Read more
Enhanced photo-transfection efficiency of mammalian cells on graphene coated substrates

Author: Mthunzi-Kufa, Patience ; He, K ; Ngcobo, Sandile ; Warner, JW Date: Feb 2014 Literature reports graphene, an atomic-thick sheet of carbon atoms as one of the promising biocompatible scaffolds that promotes cellular proliferation in human mesenchymal stem cells. On the other hand, different mammalian cell lines including ... Read more
Excitation of high-radial-order Laguerre-Gaussian modes in a solid-state laser using lower-loss digitally controlled amplitude mask

Author: Bell, Lebohang T ; Hasnaoui, A ; Ait-Ameur, K ; Ngcobo, Sandile Date: Sep 2017 In this paper, we experimentally demonstrate selective excitation of highradial-order Laguerre-Gaussian (LGp or LGp;0) modes with radial-order, p = 1 - 4 and azimuthal-order, l = 0, using a diode-pump solid-state laser (DPSSL) that is digitally ... Read more
Generating higher-order radial Laguerre-Gaussian modes using a digital laser

Author: Bell, Teboho ; Ngcobo, Sandile ; Haddadi, S ; Ait-Ameur, K ; Forbes, A Date: Jul 2015 Using the digital laser one can generate various types of modes, like, Laguerre-Gaussian modes. The digital laser was forced to generate high-order radial Laguerre-Gaussian modes, LGp , with zero azimuthal order, by loading a digital hologram ... Read more
Generation of high order modes

Author: Ngcobo, Sandile ; Ait-Ameur, K ; Forbes, A Date: Jul 2012 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 geometry is in ... Read more
Generation of Laguerre-Gaussian Beams Using a Diode Pumped Solid-State Digital Laser

Author: Bell, Teboho ; Forbes, A ; Ngcobo, Sandile Date: Oct 2015 The solid state digital laser was used in generation of Laguerre-Gaussian modes, LGpl, of different orders. This work demonstrates that we can generate high-order Laguerre-Gaussian modes with high purity using a digital laser. Read more
Generation of Radial Laguerre-Gaussian modes with a lower threshold using a digital laser

Author: Bell, Teboho ; Haddadi, S ; Ait-Ameur, K ; Forbes, A ; Ngcobo, Sandile Date: Jul 2015 This poster discusses the generation of Radial Laguerre-Gaussian modes with a lower threshold using a digital laser. Read more
Generation of shape-invariant flat-top laser beams

Author: Ait-Ameur, K ; Naidoo, Darryl ; Ngcobo, Sandile ; Fromager, M ; Litvin, I ; Hasnaoui, A ; Harfouche, A ; Forbes, A Date: Feb 2015 A great number of laser applications need in place of the usual Gaussian beam a flat-top intensity profile in the focal plane of a focusing lens. In general the transformation of the laser beam from the Gaussian to the flat-top shape is made ... Read more
Graphene for improved femtosecond laser based pluripotent stem cell transfection

Author: Mthunzi-Kufa, Patience ; He, K ; Ngcobo, Sandile ; Khanyile, T ; Warner, JH Date: May 2014 Pluripotent stem cells are hugely attractive in the tissue engineering research field as they can self-renew and be selectively differentiated into various cell types. For stem cell and tissue engineering research it is important to develop ... Read more
Graphene substrates enhance optical transfection efficiency in pluripotent stem cells

Author: Khanyile, T ; He, K ; Ngcobo, Sandile ; Warner, JH ; Mthunzi-Kufa, Patience Date: Sep 2013 Studies directed at investigating the role of nanomaterial substrates with varying properties in tissue engineering research are essential. In this research arena, pluripotent stem cells are popular for their self renewing ability and are ... Read more
High Efficient LGp0 End Pumped Nd:YAG Laser

Author: Ngcobo, Sandile ; Forbes, A ; Ait-Ameur, K Date: Jul 2012 The transformation of a single mode TEM00 Gaussian beam by forcing the laser to operate into a symmetrical single mode higher order TEMp0 Laguerre Gaussian beam intensity distribution is very useful in improving and substantially increasing ... Read more
How to make a digital laser

Author: Burger, L ; Litvin, I ; Ngcobo, Sandile ; Forbes, A Date: Mar 2014 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 beams. For every ... Read more
Intra-cavity generation of high order LGpl modes

Author: Ngcobo, Sandile ; Ait-Ameur, K ; Forbes, A Date: Aug 2012 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 geometry is in ... Read more
Modal decomposition without a priori scale information

Author: Schulze, C ; Ngcobo, Sandile ; Duparre, M ; Forbes, A Date: Dec 2012 The modal decomposition of an arbitrary optical field may be done without regard to the spatial scale of the chosen basis functions, but this generally leads to a large number of modes in the expansion. While this may be considered as ... Read more

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