Dresden 2011 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 15: Poster 1: Quanteninformation, Quanteneffekte, Laserentwicklung, Laseranwendungen, Ultrakurze Pulse, Photonik

Q 15.9: Poster

Montag, 14. März 2011, 16:30–19:30, P1

High Power THz Generation in a Thin Lithium Niobate Slab using a Non-Collinear Cherenkov-Type Geometry — •Ulrich Arthur Fromme, Benjamin Ewers, Maik Scheller, Sangam Chatterjee, and Martin Koch — Department of Physics and Material Sciences Center, Philipps-Universität Marburg, Renthof 5, D 35032 Marburg

In the field of non-linear terahertz (THz) spectroscopy, there is a growing demand for THz emitters strong enough to induce significant non-linear effects. But since the optically gated THz antennas usually used to generate THz pulses already saturate at moderate laser intensities, they cannot convert extremely high pump energies efficiently. Another method to achieve strong THz emission is optical rectification, a χ⁽²⁾ process which generates strong THz radiation at high laser pump powers. In this work, lithium niobate (LiNbO₃) is used to convert intense pulses of infrared light into THz waves. A simple thin slab of bulk LiNbO₃ is illuminated with the light of a regenerative Ti:Sapphire amplifier system in a non-collinear Cherenkov-type geometry. To overcome the total reflection of the THz waves at the LiNbO₃-air interface, a silicon prism is contacted to the crystals surface. Using an additional diffractive grating to tilt the lasers wave front allows for phase matching between the optical and the THz pulses in the utilized geometry. Thus, conversion efficiencies up to 10⁻⁴ and peak electric fields strengths of 50 kV/cm are obtained at pump pulse energies of 450 µ J. We investigate the effect of changing the tilt angle of the wave on the generated THz amplitude and spectrum.