Two-photon absorption and nonlinear optical properties of a new organic dye PSPI

Trans-4-[p-(pyrrolidinyl)styryl]-N-methylpyridinium iodide (abbreviated as PSPI thereafter) is a two-photon absorption (TPA) dye newly synthesized by our research group. It possesses much larger TPA cross-section and much str onger upconversion fluorescence emission than those of common organic dye ( such as rhodamine) when excited with near infrared (IR) radiation. TPA spec trum and upconversion efficiency spectrum of HEASPI solution at various wav elengths were measured. There is 34 nm blue shift for the central wavelengt h of the TPA induced absorption peak compared with two times of the linear absorption peak. The biggest molecular TPA cross-section sigma (2) is 2.85 x 10(-47) cm(4) s/photon at 930 nm. At 1064 nm, sigma (2) is 3.12 x 10(-48) cm(4) s/photon. The highest efficiency is 3.9% at 1010 nm, whereas 2.9% at 1064 nm. Its optical power limiting properties at 930 nm have also been il lustrated. (C) 2001 Elsevier Science B.V. All rights reserved.