Faculty Publications
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Item Studies on third-order nonlinear optical properties of chalcone derivatives in polymer host(Elsevier, 2008) Shettigar, S.; Umesh, G.; Chandrasekharan, K.; Sarojini, B.K.; Narayana, B.In this paper we present the experimental study of the third-order nonlinear optical properties of two chalcone derivatives, viz., 1-(4-methoxyphenyl)-3-(4-butyloxyphenyl)-prop-2-en-1-one and 1-(4-methoxyphenyl)-3-(4-propyloxyphenyl)-prop-2-en-1-one in PMMA host, with the prospective of reaching a compromise between good processability and high nonlinear optical properties. The nonlinear optical properties have been investigated by Z-scan technique using 7 ns laser pulses at 532 nm. The nonlinear refractive index, nonlinear absorption coefficient, magnitude of third-order susceptibility and the coupling factor have been determined. The values obtained are of the order of 10-14 cm2/W, 1 cm/GW, 10-13 esu and 0.2, respectively. The molecular second hyperpolarizability for the chalcone derivatives in polymer is of the order of 10-31 esu. Different guest/host concentrations have also been studied. The results suggest that the nonlinear properties of the chalcones have been improved when they are used as dopants in polymer matrix. The nonlinear parameters obtained are comparable with the reported values of II-VI compound semiconductors. Hence, these chalcons are a promising class of nonlinear optical dopant materials for optical device applications. © 2007 Elsevier B.V. All rights reserved.Item Third-order optical nonlinear studies of Cobalt (II) Schiff base complex bearing triphenylphosphine using Differential Optical Kerr Gate and Z-scan studies(2010) Rudresha, B.J.; Badekai Ramachandra, B.; Ramakrishna, D.; Anthony, J.K.; Rotermund, F.The third-order optical nonlinearity of the composite film of coordination complex [CoLPPh3Cl] (L = N-(2-pyridyl)-N?-(salicylidene)hydrazine) and PMMA has been investigated by using Differential Optical Kerr Gate (DOKG) and Z-scan measurements. Large value of the third-order nonlinear optical susceptibility (?(3)) of the order of 10-10 esu was measured and its nonlinear response time was found to be faster than or comparable to the laser pulse width (90 fs) used. The single beam Z-scan technique was used to investigate the nonlinear absorption property of the composite near 800 nm. The sample exhibit saturable absorption. The nonlinear absorption coefficient of sample is found to be -32 cm/GW. © 2010 Elsevier B.V. All rights reserved.Item Synthesis, characterization and studies on the nonlinear optical parameters of hydrazones(2010) Naseema, K.; Sujith, K.V.; Manjunatha, K.B.; Kalluraya, B.; Umesh, G.; Rao, V.Three hydrazones, 2-(4-methylphenoxy)-N?-[(1E)-(4-nitrophenyl)methylene]acetohydrazide (compound-1), 2-(4-methylphenoxy)-N?-[(1E)-(4-methylphenyl)methylene]acetohydrazide ((compound-2) and N?-{(1E)-[4-(dimethylamino)phenyl]methylene}-2-(4-ethylphenoxy) acetohydrazide(compound-3) were synthesized and their third order nonlinear optical properties were investigated using a single beam z-scan technique with nanosecond laser pulses at 532 nm. Open aperture data obtained from the three compounds indicates two photon absorption at this wavelength. The nonlinear refractive index n2, the nonlinear absorption coefficient ?, the magnitude of the effective third order susceptibility ?(3), the second order hyperpolarizability ?h and the coupling factor ? have been estimated. The values obtained are comparable with the values obtained for 4-methoxy chalcone derivatives and dibenzylidene acetone derivatives. Among the compounds studied, compounds-1 and 3 exhibited the better optical power limiting behaviour at 532 nm. Our studies suggest that compounds-1, 2 and 3 are potential candidates for optical device applications such as optical limiters and optical switches. © 2009 Elsevier Ltd. All rights reserved.Item Synthesis, characterization and studies on nonlinear optical parameters of 4-amino-5-(4-nitrophenyl)-1, 2, 4-triazole-3-thione(2010) Naseema, K.; Rao, V.; Manjunatha, K.B.; Umesh, G.; Sujith, K.V.; Kalluraya, B.In this paper, we report the synthesis, characterization and third order nonlinear optical properties of a new organic NLO material of 4-amino-5-(4-nitrophenyl)-1, 2, 4-triazole-3-thione (ANIT). The material was characterized by UV-vis and FTIR studies. The third order nonlinear optical properties have been investigated in dimethyl formamide (DMF) solution at 532 nm by using the Z-scan technique with pulses of nanoseconds duration. Open aperture data demonstrates the presence of two photon absorption at this wavelength. The nonlinear absorption coefficient ?, the nonlinear refractive index n2, the magnitude of effective third order susceptibility ?(3) and the second order hyperpolarizability ?h have been estimated as 2.99 cm/GW, -2. 53?×?10-11 esu, 2.72?×?10 -13esu and 0.281?×?10-31esu respectively. The values obtained are comparable with the values obtained for 4-methoxy chalcone derivatives and dibenzylideneacetone derivatives. The value of coupling factor have been estimated to be 0.17, indicating that the nonlinearity is electronic in origin. The compound exhibits good optical limiting at 532 nm with the limiting threshold of 80 ?J/pulse. The comparatively high value obtained indicates that this material may be used in optical device applications like optical limiters and optical switches. © 2010 Optical Society of India.Item Synthesis and third order optical nonlinearity studies of the donor-acceptor conjugated polymer, poly(2-[3,4-didodecyloxy-5-(1,3,4-oxadiazol- 2-yl)thiophen-2-yl]-5-phenyl-1,3,4-oxadiazole) and a polymer/TiO2 nanocomposite(2010) Murali, M.G.; Ramya, M.G.; Udayakumar, D.; Lakshmi, N.B.; Philip, R.A donor-acceptor conjugated polymer (PDOThPOD) containing 3,4-didodecyloxythiophene and (1,3,4-oxadiazolyl)benzene units is synthesized by using precursor polyhydrazide route. Cyclic voltammetry studies reveal that the polymer possesses a low-lying LUMO energy level (-3.57 eV). A nanocomposite of polymer PDOThPOD and nano TiO2 is also prepared. The linear optical properties of PDOThPOD and the nanocomposite are studied using UV-vis absorption spectroscopy and fluorescence emission spectroscopy. z-scan technique is used to study the third order nonlinear optical properties of the polymer and nanocomposite films. Both polymer and nanocomposite films show a strong optical limiting behavior. The value of nonlinear absorption coefficient (?) is found to be of the order of 10-7 m/W, indicating that these materials are potentially suited for fabricating optical limiters. © 2010 Elsevier B.V. All rights reserved.Item ?(3) measurement and optical limiting studies of urea picrate(2011) Naseema, K.; Shyma, M.; Manjunatha, K.B.; Muralidharan, A.; Umesh, G.; Rao, V.The molecular charge complex urea picrate (UP) was synthesized and its third order nonlinear optical properties have been investigated using a single beam Z-scan technique with nanosecond laser pulses at 532 nm. Open aperture data of the compound indicates two photon absorption at this wavelength. The nonlinear refractive index n2, nonlinear absorption coefficient ?, magnitude of effective third order susceptibility ?(3), the second order hyperpolarizability ?h and the coupling factor ? have been estimated. The experimentally determined values of ?, n2, Re ?(3) and Im ?(3), ?h and ? of the compound UP are 2.146 cm/GW, -1.258×10-11 esu, -1.347×10-13 esu, 0.377×10-13 esu, 0.69×10-32 esu and 0.28, respectively. The compound exhibits good optical limiting at 532 nm with the limiting threshold of 80 ?J/pulse. Our studies suggest that compound UP is a potential candidate for optical device applications such as optical limiters. © 2011 Elsevier Ltd. All rights reserved.Item Third order optical nonlinearity and optical limiting studies of propane hydrazides(Elsevier B.V., 2012) Naseema, K.; Manjunatha, K.B.; Sujith, K.V.; Umesh, G.; Kalluraya, B.; Rao, V.Four hydrazones, 2-(4-isobutylphenyl)-N?-[phenylmethylene] propanehydrazide (P1), 2-(4-isobutylphenyl)-N?-[(4- tolyl)methylene] propane hydrazide (P2), 2-(4-isobutylphenyl)- N?-[1-(4- chlorophenyl)ethylidene] propanehydrazide (P3) and 2-(4-isobutylphenyl)-N?-[1-(4-Nitrrophenyl)ethylidene] propane hydrazide (P4) were synthesized and their third order nonlinear optical properties have been investigated using a single beam Z-scan technique with nanosecond laser pulses at 532 nm. The measurement on the compound-P1 is not reported as there is no detectable nonlinear response. Open aperture data of the other three compounds indicate two photon absorption at this wavelength. The nonlinear refractive index n2, nonlinear absorption coefficient ?, magnitude of effective third order susceptibility ?(3), the second order hyperpolarizability ?h and the coupling factor ? have been estimated. The values obtained are comparable with the values obtained for 4-methoxy chalcone derivatives and dibenzylideneacetone derivatives. The experimentally determined values of ?, n2, Re ?(3) and Im ?(3), ?h and ? of the compound-P4 are 1.42 cm/GW, -0.619 × 10-11 esu, -0.663 × 10-13 esu, 0.22 × 10-13 esu, 0.34 × 10-32 esu and 0.33 respectively. Further the compound-P4 exhibited the best optical power limiting behavior at 532 nm among the compounds studied. Our studies suggest that compounds P2, P3 and P4 are potential candidates for the optical device applications such as optical limiters and optical switches. © 2012 Elsevier B.V. All rights reserved.Item Nonlinear optical study of palladium Schiff base complex using femtosecond differential optical Kerr gate and Z-scan techniques(2012) Rudresha, B.J.; Badekai Ramachandra, B.R.; Ramakrishna, D.; Anthony, J.K.; Lee, H.W.; Rotermund, F.A femtosecond differential optical Kerr gate (DOKG) and Z-scan techniques, have been applied to investigate the third-order optical nonlinearity of composite film of the coordination complex [PdLPPh 3] (L=N-(2-pyridyl)-N'-(salicylidene)hydrazine, PPh 3=triphenylphosphine) . Film exhibits superior nonlinear optical properties in the near-infrared spectral region. The nonlinear response time and third-order nonlinear optical susceptibility of complex were found to be?90 fs and 3.9×10 -10 esu, respectively. The Z-scan result shows that saturable absorption property of the film and its nonlinear absorption coefficient of the sample was found to be -23 cm/GW. © 2011 Elsevier Ltd. All rights reserved.Item Effect of annealing on the structural and nonlinear optical properties of ZnO thin films under cw regime(2013) Nagaraja, K.K.; Pramodini, S.; Poornesh, P.; Nagaraja, H.S.We report on the studies of the effects of annealing on the structural and third-order nonlinear optical properties of ZnO thin films deposited on quartz substrates by the RF magnetron sputtering technique. The films were annealed in the temperature range 400-1000 °C. The third-order nonlinear optical studies were carried out using the z-scan technique under continuous wave (cw) He-Ne laser irradiation at 633 nm wavelength. The effects of annealing on the structural properties were examined using x-ray diffraction and atomic force microscopy (AFM). The (0 0 2) preferred orientation increased with increase in annealing temperature up to 800 °C. The crystalline phases of SiO2 were observed at higher annealing temperatures. The appearance of an extraneous phase was confirmed by AFM images and optical transmittance spectra. The samples exhibited nonlinear absorption and nonlinear refraction under the experimental conditions. The negative sign of the nonlinear refractive index n2 indicated that the films exhibit self-defocusing property due to thermal nonlinearity. The nonlinear refractive index n2, the nonlinear absorption coefficient ?eff and the third-order optical susceptibility ?(3) were found to be of the highest orders. The estimated value of third-order optical susceptibility ?(3) was of the order of 10-3 esu. Multiple diffraction rings were observed when the samples were exposed to the laser beam. The appearance of rings was due to the refractive index change and thermal lensing. With increase in laser intensity, the variations of the self-diffraction ring patterns were studied experimentally. The films also exhibited strong optical limiting properties under cw laser excitation, and reverse saturable absorption was the dominant process leading to the observed nonlinear behaviour. © 2013 IOP Publishing Ltd.Item Synthesis, characterization and evaluation of the photophysical and nonlinear optical behaviour of novel 4-substituted arylidene-2-[5-(2,6- dichlorophenyl)-3-methyl-1,2-oxazol-4-yl]-1,3-oxazol-5-ones(2013) Murthy, Y.L.N.; Kilaru, K.P.; Veeraiah, V.; Umesh, G.; Manjunatha, K.B.; Christopher, V.Five new 4-substituted arylidene-2-[5-(2,6-dichlorophenyl)-3-methyl-1,2- oxazol-4-yl]-1,3-oxazol-5-ones have been designed and synthesized in order to study their third-order nonlinear optical properties. These novel compounds were characterized by advanced spectroscopic techniques (IR, 1H, 13C NMR, ESI-MS spectroscopy and elemental analyses). In addition, the evaluation of absorption and emission wavelengths of the new 5-oxazolone derivatives was carried out in seven different solvents of varying polarity, which showed intense absorption maxima at 350-480 nm and emission maxima at 390-535 nm respectively. The third-order nonlinear optical properties of the target molecules have been investigated in N,N-dimethylformamide using a single beam Z-scan technique with nanosecond laser pulses at 532 nm. The nonlinear refractive index, nonlinear absorption coefficient, magnitude of third-order susceptibility and molecular two photon absorption cross-sections have been determined. All of the compounds showed excellent optical limiting behaviour at 532 nm, with the best optical limiting behaviour observed with strong electron donor [dimethyl and N,N-diethyl amino] substituents. © 2013 Elsevier Ltd. All rights reserved.