Paper
24 April 2001 Most efficient beams for frequency mixing in second-order nonlinear crystals
Vittorio C. Magni
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Abstract
It is not established, in principle, that gaussian beams are the most efficient ones for optical sum and difference frequency generation in second order nonlinear crystals; in fact, other profiles, such as Bessel and supergaussian shaped beams have been proposed to enhance the efficiency. Here, we analyze this problem and show what beams give the absolute maximum power conversion efficiency. The analysis, which neglects the pump power depletion, is based on the beam expansion in series of Laguerre-Gauss modes and on the numerical determination of the expansion coefficients that maximize the conversion efficiency. The optimal profiles have a flat wave front at the center of the crystal and a transverse profile similar to a gaussian curve, except for a weak ring of intensity surrounding the central peak. The absolute maximum of the efficiency is not much greater than the value obtainable with optimally focused gaussian beams. For second harmonic generation a detailed comparison of the optimal beam to supergaussian beams and to Bessel-like beams is also presented.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Vittorio C. Magni "Most efficient beams for frequency mixing in second-order nonlinear crystals", Proc. SPIE 4270, Laser Resonators IV, (24 April 2001); https://doi.org/10.1117/12.424649
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KEYWORDS
Crystals

Second-harmonic generation

Gaussian beams

Laser crystals

Nonlinear crystals

Beam shaping

Phase matching

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