Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
7 results
Search Results
Item Effect of polymer host on third order nonlinear optical properties of newly synthesized organic liquid crystal(2007) Shettigar, S.; Umesh, G.; Poornesh, P.; Murthy, Y.L.N.We report the investigation of third order optical nonlinearity of 2,4,6-tri-(p-hyptoyoxylphenyl) pyrilium tetraborate doped PMMA using nanosecond laser pulses at 532nm wavelength by employing Z-Scan technique. To see the effect of polymer host, the results have been compared with the pure dopant. The material shows a large negative nonlinearity with real and imaginary parts of X(3) are - 3.31×10-14esu and 0.73×10 -14esu respectively. Excited state absorption cross-section is found to be 3.41×10-48 cm4.s/photon in PMMA host. The magnitude of third order nonlinear parameters increases when the compound is doped into PMMA matrix because of change in the conformation of chain geometry as a result of charge transfer processes. The values are comparable with a best known nonlinear liquid crystal molecule namely, 4-cyano-4'-n-pentylbiphenyl in the nematic phase. Hence, these molecules can be suitably used as nonlinear optical materials in PMMA matrix for device applications. © 2007 IEEE.Item Third order nonlinear optical properties and two photon absorption in newly synthesized phenyl sydnone doped polymer(2007) Shettigar, S.; Umesh, G.; Chandrasekharan, K.; Kalluraya, B.We have investigated third order nonlinear optical properties of three newly synthesized 3-phenyl sydnones, doped into PMMA and determined both real and imaginary part of ?(3). The measurements were performed using nanosecond laser pulses at 532 nm wavelength by employing Z-Scan technique. The nonlinear refractive index is found to be of the order of 10-14 cm2/W. The magnitude of third order susceptibility is of the order of 10-13 esu. Their two photon absorption coefficient and absorption cross section have also been determined. The optical power limiting behavior of sydnone moieties doped PMMA was also investigated. The results suggest that among the three organic phenyl sydnone moieties, 2-benzylhydrazono-5-(3-p-tolylsydnone-4-yl)1,3,4,-thiadiazine doped PMMA is a promising class of nonlinear optical material due to its simple molecular structure with p-tolyl group. It also shows a very good optical limiting behaviour with a limiting threshold of 0.21 mJ/pulse. The nonlinear parameters obtained are comparable with the values obtained in stilbazolium like dye such as trans-4-[2-(pyrrl)vinyl]-1-methylpyridium iodide. Hence this material may be tailored suitably for applications such as optical power limiters, switches and modulators. © 2007 Elsevier B.V. All rights reserved.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 nonlinear optical properties and two-photon absorption in polymers doped with p-phenyl sydnone(2008) Shettigar, S.; Umesh, G.; Chandrasekharan, K.; Rai, G.; Kalluraya, B.We report the measurements of the third-order susceptibilities and two-photon absorption in three different polymers doped with p-phenyl sydnone moiety viz., 2-benzylhydrazono-5-(3-p-tolylsydnone-4-yl)1,3,4,-thiadiazine, which is recently synthesized and characterized, with the prospective of reaching a good compromise between processability and high nonlinear optical properties. The measurements were done using nano second Z-scan at 532 nm. The Z-scan spectra reveal a large negative nonlinear refraction coefficient n 2 of the order 10-14 cm2/W and a two-photon absorption ?, which is determined to be the order of cm/GW. The absorption cross section is 10-46 cm4 s/photon. The molecular second-order hyperpolarizability in PMMA matrix was calculated to be 1.47 × 10-31 esu, comparable with stilbazolieum derivatives, a well-known class of optical materials for photonics and biophotonics applications. The chromophore shows its optical power limiting behavior in all the three polymer matrices. All these results suggest that this moiety has potential for the application of all-optical limiting and switching devices. © 2008 Wiley Periodicals, Inc.Item Nonlinear optical studies on 1,3-disubstituent chalcones doped polymer films(Elsevier, 2009) Poornesh, P.; Shettigar, S.; Umesh, G.; Manjunatha, K.B.; Prakash Kamath, K.; Sarojini, B.K.; Narayana, B.We report the measurements of the third-order nonlinear optical properties of recently synthesized and characterized two different 1,3-disubstituent chalcones doped PMMA films, with the prospective of reaching a good compromise between processability and high nonlinear optical properties. The measurements were done using nanosecond Z-scan at 532 nm. The Z-scan spectra reveal a large negative nonlinear refraction coefficient n2 of the order 10-11 esu and the molecular two photon absorption cross section is 10-46 cm4 s/photon. The doped films exhibit good optical power limiting property under nanosecond regime and the two photon absorption (TPA) is the dominating process leading to the nonlinear behavior. The improvement in the nonlinear properties has been observed when methylenedioxy group is replaced by dimethoxy group due to increase in conjugation length. The observed nonlinear parameters of chalcone derivatives doped PMMA film is comparable with stilbazolieum derivatives, a well-known class of optical materials for photonics and biophotonics applications, which suggests that, these moieties have potential for the application of all-optical limiting and switching devices. © 2008 Elsevier B.V. All rights reserved.Item The third-order nonlinear optical properties of novel styryl dyes(2009) Shettigar, S.; Umesh, G.; Poornesh, P.; Manjunatha, K.B.; Asiri, A.M.The third-order nonlinear optical properties of two novel styryl dyes, namely, 1,3-diethyl-5-(4-methoxybenzylidene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione and 5-(3,4-dimethoxybenzylidene)-1,3-diethyl-2-thioxodihydropyrimidine-4,6(1H,5H)-dione were studied using the Z-scan technique employing 7 ns laser pulses at 532 nm. The nonlinear refractive index, nonlinear absorption coefficient, magnitude of effective third-order susceptibility and coupling factor were determined. The optical power limiting behavior of the colorants was ascribed to two-photon absorption phenomenon. Nonlinear absorption cross-section increased with increase in ? electron density and the effective two-photon absorption cross-section was two orders of magnitude larger than those of commercially available azo compounds. The results suggest that these colorants offer promise as nonlinear optical materials for device applications. © 2009 Elsevier Ltd. All rights reserved.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.