Bonn 2000 – scientific programme
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Q: Quantenoptik
Q 22: Nichtlineare Optik III
Q 22.1: Talk
Wednesday, April 5, 2000, 09:00–09:15, HS XV
Second harmonic generation by higher-order Bessel beams — •Suren Soghomonyan, Ulrich T. Schwarz und Max Maier — Naturwissenschaftliche Fakultät II - Physik, Universität Regensburg, D-93040 Regensburg, Germany.
We present experimental results on second harmonic (SH) generation by higher-order Bessel beams (λ=1064 nm, Δ t=10 ns) in LiIO3 and KDP crystals. Azimuthal phase structure, near and far field intensity distribution of the SH beam have been studied for different crystal-beam configurations. We studied, in particular, the SH radiation of a first order Bessel beam J1(α r) exp(i φ) generated in a crystal with acceptance angle larger than the Bessel beam cone angle. It has a spiral wavefront dislocation of double topological charge caused by the doubling of the azimuthal phase term exp(i φ) of the pump beam in the quadratic nonlinear medium. For a Bessel beam cone angle γω=2.7 mrad the far field of the SH beam consists of a bright central spot (0.6 mrad) with very narrow minimum (< 0.05 mrad) in the center and a weak ring with angular radius γ2ω nearly equal to that of the pump beam (γ2ω=0.95 γω).