Abstract

The three-photon absorption in nanostructure wide-band ZnO semiconductor material is observed under low
intensity nanosecond Nd-YAG laser of 1.06 μm wavelength excitation. The measured nonlinear absorption
coefficient was 0.058cm3/Gwatt2 which is about two order of magnitude higher than its value in solid. The
Z-scan measurements show that the threshold laser pumping intensity required to generate the 3photon
absorption is very low compared to that for solid. The developed mathematical relation helps in the
determination of the nonlinear coefficients from the direct measurements of the emitted fluorescent. The
observation of the three-photon absorption under low intensity in nanocrystalline material attributed to the
resonance between the3??Yag and flu. ?? which is simply achieved in nanostructure.

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