Frankfurt 2006 – wissenschaftliches Programm
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Q: Quantenoptik und Photonik
Q 55: Nichtlineare optische Effekte und Lichtquellen II
Q 55.4: Vortrag
Mittwoch, 15. März 2006, 14:45–15:00, H14
Scaling up the energy of THz pulses created by optical rectification — •Ida Z. Kozma1, Andrej G. Stepanov2, Gábor Almási3, Jürgen Kuhl2, János Hebling3, and Eberhard Riedle1 — 1LS für BioMolekulare Optik, Ludwig-Maximilians-Universität, München — 2Department of Experimental Physics, University of Pécs, Hungary — 3Max-Planck-Institute for Solid State Research, Stuttgart
The possibility for up-scaling the energy of sub-ps THz pulses generated by tilted pulse front excitation is demonstrated. Using 150-fs-long 500 µJ optical pump pulses at 800 nm up to 240 nJ THz pulse energy has been achieved [1]. For a 1.2 mm2 pump spot area, the energy conversion efficiency of pump energy to THz pulse energy had a maximum of 5·10−4 at 300 µJ pump pulse energy. The corresponding photon conversion efficiency amounts to 10 %. For comparison, the maximum attainable THz pulse energy was limited to 2.1 nJ if a line focusing excitation geometry was utilized. This limit was reached at 32 µJ pump energy. For the latter configuration the THz energy dropped for larger pump energies. In order to illustrate the very different type of development of the THz pulse inside the electro-optical crystal, results of model calculations are presented for both excitation geometries. The numerical simulations are in good agreement with the experimental results. The tilted pulse front excitation allows further up-scaling of the THz pulse energy by using a larger pump spot size and still stronger pump pulses. This set-up is an attractive source of THz pulses applicable for linear and nonlinear spectroscopic investigations as well as for large area THz imaging. [1] A. G. Stepanov, et al. Opt. Express 13, 5762 (2005)