GENERATION OF THE SECOND HARMONIC OF LASER RADIATION IN POWDERS OF PURE AND DOPED POTASSIUM NITRATE IN THE TEMPERATURE INTERVAL OF 25–160 ВєC
B. I. Kidyarov1, V. I. Kovalevskii2, V. K. Malinovsky2, A. M. Pugachev2, A. F. Rozhkov3
1Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent’eva 13, Novosibirsk, 630090 Russia
kidysrov@isp.nsc.ru
2Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, pr. Akademika Koptyuga 1, Novosibirsk, 630090 Russia
mvk@iae.nsk.su
3Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, pr. Akademika Koptyuga 5, Novosibirsk, 630090 Russia
rozhkov@igm.nsc.ru
Keywords: potassium nitrate, crystal growth, ferroelectric phase transition, generation of the second harmonic
Abstract
The temperature dependence of the intensity of generation of the second harmonic of laser radiation with λ = 1.064 µm in various powders of extra-pure potassium nitrate is studied. The powders are obtained from crystals grown in a KNO3–Ba(NO3)2–H2O water–salt system. It is demonstrated that the centrosymmetric phase is crystallized from pure solutions. If Ba(NO3)2 is added to the solution, non-centrosymmetric phases of KNO3 or 2KNO3 · Ba(NO3)2 double salt are formed. As the crystals are cooled down from the temperature of 160 ºC, the samples display a ferroelectric phase transition and a hysteresis relaxation dependence of the nonlinear optical response due to the method of sample preparation.
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