Hannover 2003 – wissenschaftliches Programm
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Q: Quantenoptik
Q 36: Femtosekunden: Analyse und Spektroskopie (gemeinsam mit MO)
Q 36.8: Vortrag
Donnerstag, 27. März 2003, 12:45–13:00, B302
Geometrical optical modelling of femtosecond setups having angular dispersion — •Ida Z. Kozma1,2, Janos Hebling2, and Jürgen Kuhl3 — 1LS für BioMolekulare Optik, Sektion Physik, Ludwig-Maxilimians-Universität München — 2Department of Experimental Physics, University of Pecs, Hungary — 3Max-Planck-Institut für Festkörperforschung, Stuttgart
We present a reliable and efficient method based on geometrical optics to model propagation of ultrashort pulses in optical systems. It is shown that the commonly used method to determine the delay of the spectral groups of a pulse from the geometrical optical path length of its spectral components is only correct for aberration-free optical systems. In case of systems with angular dispersion and imaging errors, a correction to the optical path length values obtained from ray-tracing calculations must be applied. For specific systems, negligence of such a correction causes significant errors. A technique to perform this correction is presented.
An optical arrangement used for the generation and detection of tunable THz radiation by the femtosecond tilted-pulse-front excitation technique is analyzed to demonstrate the indispensability of the correction. Implementing the modeled optical system, velocity-matched efficient ultrashort THz pulse generation has been achieved in LiNbO3 by tilting the pulse front of the excitation pulses provided by a Ti:sapphire laser. The generated broad-band THz radiation has a divergence smaller than 30 mrad, and a central frequency larger than 2 THz. The energy conversion efficiency is close to 10−5.