Faculty Publications
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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 Investigation of third-order nonlinear optical properties of conjugated benzodioxal derivatives(2010) Shettigar, S.; Poornesh, P.; Umesh, G.; Sarojini, B.K.; Narayana, B.; Prakash Kamath, K.An investigation of third-order nonlinear optical characterization of newly synthesized conjugated benzodioxal derivatives has been done by using nanosecond Z-scan technique at 532 nm. The molecules demonstrate self-defocusing effect with intensity dependent refractive index (n2) of the order of 10-14 cm2/W. The measured molecular TPA cross-section is ranging from 2.47 ×10-47 cm4 s/photon to 6.00 cm4 s/photon. Their input-output curves indicate that there is a clear optical power limiting behavior with the limiting threshold in the range 125-181 ?J. The main factor to exhibit the observed nonlinearity in these molecules is the presence of charge donor and acceptor groups. The increased conjugation length increases the nonlinear refraction and increased electron density enhances the nonlinear absorption. The molecules exhibit good nonlinear optical properties, comparable to those of regular azoaromatic compounds. Therefore, the molecules investigated here are promising candidates for optical power limiting devices. © 2010 Elsevier Ltd. 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 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.Item Optical nonlinearity, limiting and switching characteristics of novel ruthenium metal-organic complex(Elsevier B.V., 2017) Manjunatha, K.B.; Rajarao, R.; Umesh, G.; Badekai Ramachandra, B.R.; Poornesh, P.We report the nonlinear optical properties of Ruthenium metal complex a promising organic material for use in scientific and technological applications. The thin films of newly synthesized ruthenium metal–organic complex were fabricated using spin coating technique. Z-scan and degenerate four wave mixing (DFWM) techniques used to extract the third-order nonlinear optical (NLO) parameters. The data reveals the investigated material exhibited relatively large NLO properties. The pump–probe experiments shows that the switch-on and off times of the material were in the order of ?s at different pump intensities and the energy dependent transmission studies reveal good limiting property of the material in nanosecond regime. © 2017 Elsevier B.V.