Abstract

We report the study of the resonant third-order nonlinear optical response of Vanadium oxide phthalocyanine micro-crystals. The refractive and absorptive contributions to the nonlinear response at several wavelengths across resonance were determined employing the z-scan technique with a tunable picosecond pulsed laser source. The samples studied were cyclohexane suspensions of tetrakis(thiohexyl) vanadyl-phthalocyanine (VOPc) micro-crystals 40 nm in diameter produced by a reprecipitation method. Very schematically, this reprecipitation method consists of injecting an acetone solution of VOPc into a poor solvent, such as water or cyclohexane for example, that is being stirred vigorously. Micro-crystals of a well-defined particle size can be produced by controlling the cyclo-hexane temperature and stirring rate. Suspensions of micro-crystals which were 40 and 60 nm in diameter have been produced by this technique. The micro-crystal dimensions were determined by electron microscopy and dynamic light scattering measurements. These micro-crystals represent an interesting alternative for the production of solid state samples of a good optical quality through relatively simple techniques.

© 1999 Optical Society of America