Tunable THz pulse generation by optical rectification of ultrashort laser pulses with tilted pulse fronts

J. Hebling, A. G. Stepanov, G. Almási, B. Bartal, J. Kuhl

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Abstract

Optical rectification of ultrashort near-IR laser pulses with tilted pulse fronts and pulse energies of a few μJ in Mg-doped stoichiometric LiNbO 3 cooled to low temperature is a powerful technique for efficient generation of THz pulses. The pulse energy critically depends on the Mg doping (necessary for preventing photorefractive damage) and can be easily increased by a factor of three if the MgO content is reduced. Pulse energies up to 400 pJ at repetition rates of 200 kHz and 3.4% quantum conversion efficiency are achieved at 77 K. At 10 K, changing the tilt angle of the pump pulse front results in continuous tuning of the frequency across the 1.0-4.4 THz range. The temporal pulse shapes measured by electro-optic sampling are in good agreement with the signal calculated by a simple theory. This model predicts tunability on a considerably broader range and narrower spectra even at room temperature if GaSe is used instead of LiNbO3. The advantages of the velocity matching technique utilizing tilted pulse fronts are analyzed in comparison with quasi-phase-matching in periodically poled LiNbO3 crystals. The first method provides a ten times higher pulse energy conversion efficiency.

Original languageEnglish
Pages (from-to)593-599
Number of pages7
JournalApplied Physics B: Lasers and Optics
Volume78
Issue number5
DOIs
Publication statusPublished - Mar 1 2004

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ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)
  • Physics and Astronomy(all)

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