Nonlinear optical properties of water-soluble polymeric dyes with biological applications

The nonlinear optical properties of two water-soluble polymeric dyes, poly( R-478) (an anionic anthraquinone dye) and poly(S-119) (an anionic azo dye), are investigated utilizing nanosecond and femtosecond optical techniques s uch as z-scan, nonlinear transmission, and time-resolved luminescence. Poly (R-478) showed large nonlinear refraction when studied with femtosecond las er pulses at 800 nm, with a value for the intensity-dependent refractive in dex (n(I)) of 1.26 x 10(-4) cm(2)/GW. The thin film result at 1064 nm indic ated a large nonlinear absorption in both polymeric dyes. The origin of the large fast optical nonlinearities in the polymeric system S-119 was invest igated by probing the different functional groups of the polymer. The chrom ophore group (Sunset Yellow) of the S-119 polymer showed a smaller nonlinea r response when compared to the polymer result. Significant differences in the electronic dynamics between the parent poly(S-119) and the chromophore Sunset Yellow were observed by time-resolved luminescence spectroscopy. The applications of the NLO effects in these polymers are demonstrated for las er ablation of A549 lung carcinoma cells.