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Proceedings Paper

Improving the intensity of a focused laser beam
Author(s): Sofiane Haddadi; Michael Fromager; Djelloul Louhibi; Abdelkrim Hasnaoui; Ali Harfouche; Emmanuel Cagniot; Kamel Äit-Ameur
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Paper Abstract

Let us consider the family of symmetrical Laguerre-Gaus modes of zero azimuthal order which will be denoted as LGp0 . The latter is made up of central lobe surrounded by p concentric rings of light. The fundamental mode LG00 is a Gaussian beam of width W. The focusing of a LGp0 beam of power P by a converging lens of focal length f produces a focal spot keeping the LGp0 -shape and having a central intensity I0= 2PW2/(λf)2 whatever the value of the radial order p. Many applications of lasers (laser marking, laser ablation, …) seek nowadays for a focal laser spot with the highest as possible intensity. For a given power P, increasing intensity I0 can be achieved by increasing W and reducing the focal length f. However, this way of doing is in fact limited because the ratio W/f cannot increase indefinitely at the risk of introducing a huge truncation upon the edge of the lens. In fact, it is possible to produce a single-lobed focal spot with a central intensity of about p times the intensity I0. This result has been obtained by reshaping (rectification) a LGp0 beam thanks to a proper Binary Diffractive Optical Element (BDOE). In addition, forcing a laser cavity to oscillate upon a LGp0 can improve the power extract due to a mode volume increasing with the mode order p. This could allow envisaging an economy of scale in term of laser pumping power for producing a given intensity I0. In addition, we have demonstrated that a rectified LGp0 beam better stand the lens spherical aberration than the usual Gaussian beam.

Paper Details

Date Published: 3 March 2015
PDF: 8 pages
Proc. SPIE 9343, Laser Resonators, Microresonators, and Beam Control XVII, 93431R (3 March 2015); doi: 10.1117/12.2075578
Show Author Affiliations
Sofiane Haddadi, Ctr. de Développement des Technologies Avancées (Algeria)
Michael Fromager, Ctr. de Recherche sur les Ions, les Matériaux et la Photonique (CIMPA) (France)
Djelloul Louhibi, Ctr. de Développement des Technologies Avancées (Algeria)
Abdelkrim Hasnaoui, Univ. des Sciences et de la Technologie Houari Boumediene (Algeria)
Ctr. de Développement des Technologie Avancées (Algeria)
Ali Harfouche, Univ. des Sciences et de la Technologie Houari Boumediene (Algeria)
Ctr. de Développement des Technologie Avancées (Algeria)
Emmanuel Cagniot, Ctr. de Recherche sur les Ions, les Matériaux et la Photonique (CIMPA) (France)
Kamel Äit-Ameur, Ctr. de Recherche sur les Ions, les Matériaux et la Photonique (CIMPA) (France)
Ctr. de Développement des Technologie Avancées (Algeria)


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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