Scaling up the energy of THz pulses created by
A. G. Stepanov and J. Kuhl
Max-Planck-Institute for Solid State Research, D-70569 Stuttgart, Germany
I. Z. Kozma and E. Riedle
LS für BioMolekulare Optik, Ludwig-Maximilians-Universität, D-80538 München, Germany
G. Almási and J. Hebling
Department of Experimental Physics, University of Pécs, H-7624 Pécs, Hungary
Abstract: 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. For a 1.2 mm2 pump spot area, the energy conversion
efficiency of pump energy to THz pulse energy had a maximum of 5 x 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 3.1 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. 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.
© 2005 Optical Society of America
OCIS codes: (190.2620) Frequency conversion; (190.7110) Ultrafast nonlinear optics
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(C) 2005 OSA 25 July 2005 / Vol. 13, No. 15 / OPTICS EXPRESS 5762
#7467 - $15.00 US Received 16 May 2005; revised 13 July 2005; accepted 17 July 2005
line focusing excitation for comparison, the maximum THz energy was 3.1 nJ. This value was
obtained at 32 μJ pump energy. At larger pump energy, the THz energy drops for this
geometry. The experimental results are in good agreement with model calculations. The tilted
pulse front excitation allows further up-scaling of the THz energy if the pump spot size is
increased. We believe that 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.
The authors are grateful to J. P. Kotthaus for supporting the experimental work, and to C. J. F.
Dupraz for the technical assistance. I. Z. Kozma acknowledges the financial support of the
Alexander von Humboldt Foundation. This work was supported by the Hungarian Scientific
Research Fund, grant number T 038372.
(C) 2005 OSA 25 July 2005 / Vol. 13, No. 15 / OPTICS EXPRESS 5768
#7467 - $15.00 USReceived 16 May 2005; revised 13 July 2005; accepted 17 July 2005