Nonlinear optical properties of substituted pyridostyryl dye base films

The paper presents the results of the complex investigation of linear and nonlinear parameters of new organic compound type - polymethine dye base (PDB) - 1-pentafluorophenyl-4-phenyl-5,6,7,8-tetrahydro-8-[(4-dimethylaminophenyl)methylene]-quinoline. For the first time thin films on glass substrate from this material were deposited by physical evaporation in vacuum. Linear absorption spectra of base films and base solutions were investigated in the wavelength range 300 - 1100 nm. Nonlinear properties of three films with thickness of 247, 350, 535 nm were studied with Z-scan and spatial profile analysis techniques in picosecond range of pumping pulses duration at the fundamental wavelength of YAG:Nd3+ laser 1064 nm. We observed darkening/bleaching effects of different magnitude (2 - 20%) of total transmittance in dependence on films thickness. It was estimated effective third order nonlinear susceptibility χ(3) ≈ 10-5 esu. Such high nonlinear response can be explained by presumable cascade process of PDB molecule excitation which is simultaneously in resonance with pump wavelength 1064 nm (1.17 eV) and its harmonics 355 nm (3.48 eV).© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.