We present experimental data for the irradiance dependence of the optical nonlinearity of an organic material at different wavelengths across resonance. The material studied was a suspension of vanadyl-phthalocyanine nanocrystals in cyclohexane. The refractive and absorptive contributions to the nonlinearity were resolved by use of the z-scan technique with a tunable picosecond laser source. The observed dependence of the nonlinearity with irradiance is explained by excited-state absorption, and a three-level model is used to describe the nonlinear response. A fit to the experimental data is made, allowing the extraction of molecular parameters that are of interest for a full characterization of the nonlinearity.
|Number of pages||7|
|Journal||Journal of the Optical Society of America B: Optical Physics|
|Publication status||Published - 2000 Aug|
ASJC Scopus subject areas
- Statistical and Nonlinear Physics
- Atomic and Molecular Physics, and Optics