Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
9 results
Search Results
Item Synthesis, characterization and third order nonlinear optical studies of diimine based Zn(II), Cd(II) and Hg(II) complexes(2011) Rudresha, B.J.; Badekai Ramachandra, B.R.; Manjunatha, K.B.; Umesh, G.The Zn(II), Cd(II), Hg(II) complexes bearing diimine and one-dimensional (1D) push-pull NLO-phores with Ï€-conjugation between ligands and metal have been synthesized for two-dimensional (2D) nonlinear optical response. The third-order nonlinear optical properties of complexes were studied using Z-scan technique at 532 nm with nanosecond laser pulses. The complexes show optical limiting behavior. The values of the effective two-photon absorption (2PA) coefficients (β), third-order nonlinear susceptibilities (χ( (3)) and large two-photon absorption cross sections (σ2) are calculated. Z-scan results show that complexes are suitable materials for optical limiting as well as optical switching applications. © 2011 American Institute of Physics.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 Nonlinear optical and optical power limiting studies on a new thiophene-based conjugated polymer in solution and solid PMMA matrix(2010) Poornesh, P.; Hegde, P.K.; Umesh, G.; Manjunatha, M.G.; Manjunatha, K.B.; Vasudeva Adhikari, A.V.An experimental investigation of the third-order nonlinear optical properties of new poly{2-{5-[3,4-ditetradecyloxy-5-(1,3,4-oxadiazol-2-yl)thiophen-2-yl]-1,3,4-oxadiazol-2-yl}pyridine} (P) in tetrahydrofuran (THF) solution and in solid poly(methylmethacrylate) (PMMA) matrix, by Z-scan technique is reported. The Z-scan traces reveal that the composite films exhibit large negative nonlinear refractive index of the order 10-10 esu. The excited-state absorption cross-section was found to be larger than the ground-state absorption indicating that the operating nonlinear process is reverse saturable absorption (RSA). The new polymer P exhibits good optical power limiting properties in the nanosecond regime in solution and as well in solid PMMA matrix. © 2009 Elsevier Ltd. All rights reserved.Item 3,3?-Benzene-1,4-diylbis[1-(substituted)phenylprop-2-en-1-one] derivatives: A new class of materials for third-order nonlinear optical applications(2010) Poornesh, P.; Ravi, K.; Umesh, G.; Hegde, P.K.; Manjunatha, M.G.; Manjunatha, K.B.; Vasudeva Adhikari, A.V.We have investigated the third-order nonlinear optical parameters of Bischalcones embedded in DMF solution and in solid PMMA matrix, by Z-scan technique using nanosecond laser pulse trains at 532 nm. Z-scan results reveal that the Bischalcones exhibits negative nonlinear refractive index as high as 10-11 esu. The molecular two-photon absorption cross-section ?2? of Bischalcones were of the order 10-46 cm4 s/photon, which is nearly two orders of magnitude larger than that of Rhodamine 6G which is 10-48 - 10-50 cm4 s/photon. We found that, the two-photon absorption (TPA) is the dominating nonlinear process leading to nonlinear absorption in both the cases in solution and as well as in solid medium. Based on TPA process, the Bischalcones exhibit good optical power limiting of nanosecond laser pulses at the input wavelength. The nonlinear optical parameters found to increase on enhancing the strength of the electron donor groups indicating the dependence and importance of electron donor/acceptor units on third-order nonlinear optical susceptibility ?(3). © 2009 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 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 Octupolar metal complexes for third order nonlinear optical studies(2012) Rudresha, B.J.; Manjunatha, K.B.; Umesh, G.; Badekai Ramachandra, B.R.The octupolar metal complexes [Zn(bpy)(L)] (1), [Cd(bpy)(L)] (2), [Hg(bpy)(L)] (3) (bpy = 2,2?-bipyridyl, L = 4-dimethylamino-?- cyanocinnamic acid) have been synthesized. The third-order nonlinear optical properties of complexes were studied using Z-scan technique at 532 nm with nanosecond laser pulses. The complexes show optical limiting behavior. The values of the effective two-photon absorption (2PA) coefficients (?), third-order nonlinear susceptibilities (? (3)) and two-photon absorption cross sections (? 2) are calculated. Results show, lewis acidity of metal center and molecular symmetry are two important factors for observed large TPA cross-section of metal complexes. © 2012 Elsevier B.V. All rights reserved.