Two photon induced amplified spontaneous emission at low threshold from Styryl 7 dye incorporated DNA template

Abstract

Studies on biophysical interactions between DNA-surfactant complexes and dye molecules are necessary to fully exploit its potential in optoelectronic devices. In this work investigations on nonlinear optical absorption and amplified spontaneous emission (ASE) of Styryl 7 dye (LDS 750) incorporating DNA-CTMA (deoxyribonucleic acid blended with cationic surfactant molecule, cetyltrimethyl-ammonium chloride) and PMMA (Poly methyl methacrylate) is reported. The nonlinear optical studies on the sample carried out using Z scan technique exhibits reverse saturable absorption with DNA -CTMA complex but with PMMA the sample behaves as a saturable absorber. We observed ASE at low pump energy for Styryl 7–DNA-CTMA film, when excited with a pulsed nanosecond Nd: YAG laser (λ = 532 nm) whereas ASE was not observed from dye incorporated with PMMA even with high pump energy. ASE characteristics were studied as a function of excitation energy density for the evaluation of threshold energy and exponential gain coefficient. The enhanced fluorescence and low threshold for ASE make Styryl 7 dye –DNA template a promising candidate for novel optoelectronic applications.