J. Zmija, H. Kaddouri, A. Majchrowski, Z. Mierczyk, I. V. Kityk: Pb4.7Ba0.3Ge3O11 Crystals as New Acoustically Induced Nonlinear Optical Materials

Crystal Research and Technology

Cryst. Res. Technol. 36 (2001) 527 - Abstract -

J. Zmija, H. Kaddouri**, A. Majchrowski, Z. Mierczyk, I. V. Kityk*

Institute of Applied Physics, MUT, Warsaw, Poland
*Institute of Physics Czestochowa, Poland
**LP2A, Universite of Perpignan, France

Pb_4.7Ba_0.3Ge₃O₁₁ Crystals as New Acoustically Induced Nonlinear Optical Materials

Acoustically induced optical second harmonic generation (SHG) and two-photon absorption (TPA) in ferroelectric Pb_4.7Ba_0.3Ge₃O₁₁ crystals have been found. We have found that with increasing acoustical power, the SHG for YAG:Nd laser light (lambda=1.06痠) increases and achieves its maximum value at acoustical power density about 1.75 W/cm². The evaluated SHG values were 23 % less comparing with X₂₂₂ tensor of the KDP single crystals. With decreasing temperature, the acoustically induced SHG signal strongly increases below 29 K. The maximal acoustically induced SHG has been observed at acoustical frequencies lying within the ranges 12-17 kHz, 22-23 kHz and above 26 kHz. This behavior reflects nonlinear superposition of the nonlinear optical susceptibilities stimulated by externally-induced electron-phonon anharmonicity. We have observed substantial increase of the TPA (for the acoustical power W= 1.8 W/cm²) at high hydrostatic pressures (about 16 GPa) and low temperatures (below 16 K). This one confirms complicated influence of the electron-phonon interactions in the ferroelectrics on the observed nonlinear optical dependences.

Keywords: nonlinear optical crystals, lead germanate

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