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Subject: search.filters.subject.Degenerate four-wave mixing

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    Nonlinear optical studies on new conjugated poly{2,2 l-(3,4- dialkoxythiophene-2,5-diyl) bis[5-(2-thienyl)-1,3,4-oxadiazole]}s
    (2010) Hegde, P.K.; Vasudeva Adhikari, A.V.; Manjunatha, M.G.; Suchand Sandeep, C.S.; Philip, R.
    Three new donor-acceptor type poly{2,2 1-(3,4-dialkoxythiophene- 2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole]}s (P1, P2, and P3) were synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge-transporting properties of the polymers were investigated by UV-visible, fluorescence emission spectroscopic and cyclic voltammetric studies. The polymers showed bluish-green fluorescence in solutions. The electrochemical band gaps were determined to be 2.03, 2.09, and 2.17 eV for P1, P2, and P3, respectively. The nonlinear optical properties of new polymers were investigated at 532 nm using single beam Z-scan and degenerate four-wave mixing (DFWM) techniques with nanosecond laser pulses. The polymers exhibited strong optical limiting behavior due to "effective" three-photon absorption. Values of the effective three-photon absorption (3PA) coefficients, thirdorder nonlinear susceptibilities (? (3)), and figures (F) of merit were calculated. © 2010 Wiley Periodicals, Inc.
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    Large third-order nonlinearity of new ?-conjugated donor-acceptor polymers with substituted thiophene and 1,3,4-oxadiazole moieties
    (2012) Sunitha, M.S.; Vasudeva Adhikari, A.V.; Vishnumurthy, K.A.; Safakath, K.; Philip, R.
    We present the synthesis of two newly designed, thiophene-based conjugated polymers (P1 and P2) carrying 1,3,4-oxadiazole, 3,4-dinaphthyloxy thiophene, and 3,4-dialkoxy thiophene moieties as potential NLO active materials. Their NLO properties have been investigated both by the Z-scan and degenerate four-wave mixing (DFWM) techniques using 532nm, 7 nanosecond laser pulses. The measured ? and ?(3) values for the polymers are found to be in the range of 1011m/W and 1011esu, respectively. The results indicate that they exhibit good optical-limiting behavior and are promising materials for nonlinear optical applications due to effective two-photon absorption (TPA). © 2012 Copyright Taylor and Francis Group, LLC.
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    Nonlinear optical and all-optical switching studies of palladium(II) complex
    (2013) Manjunatha, K.B.; Dileep, R.; Umesh, G.; Badekai Ramachandra, B.
    Palladium complex with Schiff-base (PdL) was synthesized and composite films were fabricated on glass substrates by the spin coating technique. Z-scan and degenerate four wave mixing (DFWM) studies on the complex were performed using Q-switched Nd:YAG 7 ns laser pulses at 532 nm to reveal the third-order nonlinear optical (NLO) parameters. The third-order NLO susceptibility (?(3)) and second-order hyperpolarizability (?h) in film form are estimated to be of the order of 10-11 and 10 -30 esu respectively. Large nonlinear absorption (NLA) due to reverse-saturable absorption (RSA) in the complex exhibits good optical power limiting (OPL) performance. All-optical switching (AOS) experiments were performed using the pump-probe method. The Z-scan investigations reveal that the switching is caused by excited-state absorption (ESA) of the He-Ne laser. © 2013 Elsevier B.V.
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    Nonlinear optical and all-optical switching studies of novel ruthenium complex
    (2013) Manjunatha, K.B.; Dileep, R.; Umesh, G.; Badekai Ramachandra, B.
    We report the experimental investigation on third-order nonlinear optical parameters of a novel (2-thioxo-1,3-dithiole-4,5-dithiolato) triphenylphosphine Ru (III) [RuL] both in solution and solid form, by using Z-scan technique at the measurement wavelength of 532 nm. The films were prepared by spin-coating technique on glass substrate. The magnitude and sign of the third-order nonlinear absorption and refractive index n2 of ruthenium complex were determined. The results reveal that ruthenium complex exhibits large negative nonlinear refractive index (n2) of the order of 10 -9 esu. The third-order nonlinear optical susceptibility (?(3)) values were of the order 10-10 esu. The nonlinear optical properties were found to vary with concentration. The ?(3) value is confirmed through degenerate four wave mixing (DFWM) experiment at the same wavelength. The effective excited-state absorption cross section was found to be larger than the ground state absorption cross section indicating that the operating nonlinear mechanism is reverse saturable absorption (RSA). It was found that the ruthenium complex exhibits good optical power limiting and also all-optical switching of nanosecond laser pulses. This new compound has potential application as photonic and optoelectronic devices. © 2013 Elsevier Ltd.