Conference Papers

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Author: search.filters.author.Hegde, P.K.

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    Nonlinear optical studies of newly synthesized polythiophenes containing pyridine and 1,3,4-oxadiazole units
    (John Wiley and Sons Inc., 2009) Poornesh, P.; Hegde, P.K.; Manjunatha, M.G.; Umesh, G.; Vasudeva Adhikari, A.V.
    We report measurements of the third-order nonlinear optical properties of a newly synthesized thiophene- based copolymer. The nonlinear transmission measurements were performed on the copolymer dissolved in tetrahydrofuran by employing the single beam Z-scan technique. Q-switched laser output at 532-nm wavelength was used for this purpose. The nonlinear absorption coefficient, β, nonlinear refractive index, n2, and the real and imaginary parts of third-order susceptibility, x(3), were, 18.93 cm/GW, 3.037 x 10 -17 m2/W (1.022 x 10-10 esu), 1.512 x 10-20 m2/V2(-1.080 x 10 -12 esu) and 0.399 x 10-20 2m/V2 (0.285 x 10 -12 esu), respectively. The excited state absorption crosssection σexc, was found to be larger than the ground state absorption crosssection σg, indicating reverse saturable absorption (RSA) in the copolymer sample. The co- polymer exhibits an optical power limiting threshold of about 120 μJ and saturated output of less than 80 μJ. Hence, the copolymer seems to be a promising material for photonic device applications. © 2008 Society of Plastics Engineers.
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    A new nonlinear optically active donor-acceptor-type conjugated polymer: Synthesis and electrochemical and optical characterization
    (2010) Manjunatha, M.G.; Vasudeva Adhikari, A.V.; Hegde, P.K.; Suchand Sandeep, C.S.S.; Philip, R.
    A new donor-acceptor-type poly[3-{5-[3,4-didodecyloxy-5-(1,3,4-oxadiazol- 2-yl)thiophen-2-yl]-1,3,4-oxadiazol-2-yl}-9-dodecyl-9H-carbazole] (P) has been synthesized through multistep reactions. The new polymer P exhibited good thermal stability and film-forming behavior. The electrochemical band gap is estimated to be 2.15 eV. The polymer emits intense green fluorescence in the solid state. Third-order nonlinear optical (NLO) studies showed that the strong absorptive nonlinearity observed for the polymer is of the optical limiting type, which is due to an "effective" three-photon absorption (3PA) process. This 3PA process can have potential applications in photonic devices. The studies revealed that the new polymer P is a promising material for development of efficient optoelectronic devices. © 2010 TMS.