Nonlinear optical measurements of BF2–aza dipyrromethene fluorophores.

Nonlinear absorption coefficient and the nonlinear refractive index of a series of BF₂ aza dipyrromethene chromophores in tetrahydrofuran (THF) solutions were measured using the Z-scan technique with a low power continuous wave laser at 633 nm. Acquired data illustrated that the process involved in nonlinear absorption is reverse saturation absorption. The excited state absorption cross sections for all complexes were calculated and a pump and probe technique was used to record the triplet absorption spectrum. The band gap of the triplet state was estimated from this spectral data and the optical limiting behavior was demonstrated for each derivative.