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Proceedings Paper

Generation of shape-invariant flat-top laser beams
Author(s): Kamel Ait-Ameur; Darryl Naidoo; Sandile Ngcobo; Michael Fromager; Igor Litvin; Abdelkrim Hasnaoui; Ali Harfouche; Andrew Forbes
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Paper Abstract

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 by a diffractive beam shaping technique. It is worthwhile to note that this transformation occurs in the vicinity of the focal plane. If a flat top laser beam keeping its shape during propagation is needed then this can be obtained by a weighted incoherent mixing of LG00 and LG01 eigenmodes. Here, we consider the generation of these two transverse modes by a solid-state laser axially pumped by a laser diode. The idea is to design the laser cavity so as to make identical the losses of LG00 and LG01 modes. To reach this objective we have used two techniques. The first one called as diffractive lies to insert an adequate amplitude mask inside the cavity. The second one called as interferometric consisted to couple the laser to an external cavity. It is important to note that LG00 and LG01 modes are not spatially in concurrence, i.e. the peak of the LG00 appears in the dip of the LG01 mode. As a result, the energy extraction from the amplifying medium is improved increasing thus the laser slope efficiency. Theory and experimental verifications have been done for the diffractive and interferometric techniques allowing the generation of a flat-top laser beam keeping its shape from the near-field to the far-field.

Paper Details

Date Published: 3 March 2015
PDF: 8 pages
Proc. SPIE 9343, Laser Resonators, Microresonators, and Beam Control XVII, 93430P (3 March 2015); doi: 10.1117/12.2075576
Show Author Affiliations
Kamel Ait-Ameur, Ctr. de Recherche sur les Ions, les Matériaux et la Photonique (France)
Ctr. de Développement des Technologies Avancées (Algeria)
Darryl Naidoo, Council for Scientific and Industrial Research (South Africa)
Sandile Ngcobo, Council for Scientific and Industrial Research (South Africa)
Michael Fromager, Ctr. de Recherche sur les Ions, les Matériaux et la Photonique (France)
Igor Litvin, Council for Scientific and Industrial Research (South Africa)
Abdelkrim Hasnaoui, Ctr. de Développement des Technologies Avancées (Algeria)
Univ. des Sciences et de la technologie Houari Boumediene (Algeria)
Ali Harfouche, Ctr. de Développement des Technologies Avancées (Algeria)
Univ. des Sciences et de la Technologie Houari Boumediene (Algeria)
Andrew Forbes, Council for Scientific and Industrial Research (South Africa)
Univ. of the Witwatersrand (South Africa)


Published in SPIE Proceedings Vol. 9343:
Laser Resonators, Microresonators, and Beam Control XVII
Alexis V. Kudryashov; Alan H. Paxton; Vladimir S. Ilchenko; Lutz Aschke; Kunihiko Washio, Editor(s)

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