Faculty Publications
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Publications by NITK Faculty
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Item Ultrafast optical response of a new metal organic complex-polymer composite film(2009) JohnKiran, A.; Lee, H.W.; Kumar, H.C.S.; Rudresha, B.J.; Badekai Ramachandra, B.R.; Yeom, D.-I.; Rotermund, F.A new Cu-based metal organic complex incorporated into poly (methyl mathacrylate) film exhibits large and fast offresonant optical nonlinearity in the 800 to 1550 nm wavelength range. A large x(3) value of l.8 x l0-10 esu is estimated. © 2009 IEEE.Item Ultrafast optical response of a new metal organic complex-polymer composite film(2009) Kiran, A.J.; Lee, H.W.; Kumar, H.C.S.; Rudresha, B.J.; Badekai Ramachandra, B.R.; Yeom, D.-I.; Rotermund, F.A new Cu-based metal organic complex incorporated into poly (methyl mathacrylate) film exhibits large and fast offresonant optical nonlinearity in the 800 to 1550 nm wavelength range. A large Χ(3) value of 1.8×10-10 esu is estimated. © 2009 IEEE.Item Non linear optical properties of banana shaped liquid crystals(2011) Nagappa; Mahadeva, J.; Somashekar, R.; Yalemaggad, C.V.; Umesh, G.; Manjunatha, K.B.We report the nonlinear absorption and refraction of banana shaped liquid crystal, namely 1,3-phynelyne bis [N-(2-hydroxy-4-n-decyloxy-benzylidene)-4'- aminobenzoate] using Z-scan technique. The measurements were carried out using a Q-switched, frequency doubled Nd:YAG laser producing 7 nanosecond laser pulses at 532nm. The Z-scan result shows that the compound exhibits negative non-linearity. The nonlinear refractive index and nonlinear absorption coefficient of this compound were found to be -1.283 × 10-11 esu and 2.232cm/GW, respectively. The real and imaginary parts of the third-order nonlinear optical susceptibility were of the order of 10 -13 esu. The results suggest that these molecules are potential nonlinear optical materials for device applications. Copyright © Taylor & Francis Group, LLC.Item Third order optical nonlinearity of a pyrazoline derivative(2011) Janardhana, K.; Ravindrachary, V.; Rajesh Kumar, P.C.R.; Yogisha; Poojary, B.; Manjunatha, K.B.; Ismayil, N.A new pyrazoline derivative 3-phenyl-5-(4-N,N-dimethylaminophenyl)-1H-2- pyrazoline (PDHP) was synthesized using standard method. The structure of the compound was established based on 1H NMR spectrum. The third-order optical nonlinear properties of PDHP compound were measured using nanosecond Z-scan method The measured nonlinear absorption coefficient β is 0.27×10-10m W-1. The magnitude of third order susceptibility is Reχ(3)==19.94×10-13 esu and Imχx (3)=5.85×10-13 esu. These experimental results reveal that the PDHP may be a good candidate for optical limiting applications due to its reverse saturated absorption phenomenon. © 2011 American Institute of Physics.Item Nonlinear optical studies of a novel pyrazoline(2012) Janardhana, K.; Ravindrachary, V.; Rajesh Kumar, P.C.R.; Umesh, G.; Manjunatha, K.B.; Ismayil, N.A novel pyrazoline, 3-(phenyl)-5-(4-hydroxyphenyl)-1-(2, 4-dinitrophenyl)-2-pyrazoline (PHDP) was synthesized using standard method and its chemical structure was confirmed using FTIR studies. The linear and non linear optical properties of the compound were studied using UV-Vis and Z-scan techniques. UV-Vis spectrum shows that the compound is transparent in the visible region and absorption in the UV region. The z-scan study shows that the compound possesses third and higher order optical nonlinearity. The calculated optical absorption cross sections indicate that the operating nonlinear mechanism is reverse saturable absorption type. The real part of the third-order nonlinear optical susceptibility χ3 was estimated and the closed aperture data shows that PHDP possess negative nonlinearity. © 2012 American Institute of Physics.Item Studies on nonlinear optical parameters of bis-chalcone derivatives doped polymer(Elsevier BV, 2006) Shettigar, S.; Chandrasekharan, K.; Umesh, G.; Sarojini, B.K.; Narayana, B.Two bis-chalcone derivatives, 1,5-[di(4-methoxyphenyl)]penta-1,4-dien-3-one and 1,5-[di(4-chlorophenyl)]penta-1,4-dien-3-one were synthesized. Their SHG conversion efficiencies are reported to be 6.0 and 5.0 times that of urea and hyper polarizabilities are 9.9×10-30 and 10.2×10-30 esu, respectively. The third-order nonlinear optical properties in PMMA matrix were studied by Z-scan technique using 7 ns laser pulses at 532 nm. The nonlinear refractive index ?, nonlinear absorption coefficient ?, magnitude of effective third order susceptibility ?(3) and the coupling factor ? have been investigated. The values obtained are of the order of 10-14 cm2/W, 1.2 cm/GW, 10-14 esu and 0.2, respectively, which are comparable with the values obtained in stilbazoleum like dyes. The experimental investigation also shows that they are very interesting optical limiting materials and their optical limiting behaviour is mainly due to two photon absorption phenomenon. © 2006 Elsevier Ltd. All rights reserved.Item ?(3) measurements and optical limiting in dibenzylideneacetone and its derivatives(2006) Kiran, A.J.; Chandrasekharan, K.; Nooji, S.R.; Shashikala, H.D.; Umesh, G.; Kalluraya, B.We investigated the third order nonlinear optical properties of dibenzylidene acetone (1,5-diphenyl-1, 4-pentadeine-3-one) and its derivatives. The nonlinear measurements were performed by using single beam Z-scan technique with Q-switched Nd:YAG nanosecond laser pulses at 532 nm. Open aperture data for dibenzylidene and its derivatives demonstrate the presence of two-photon absorption at this wavelength. The dependence of ?(3) on donor/acceptor type substituents to the basic compound clearly shows the electronic origin of nonlinearity and hence demonstrates that the mechanism by which the third order nonlinear response enhanced is not by the thermal effects, but instead due to the strong nonlinear absorption and nonlinear refraction of the compounds. The derivatives of the basic compound show very good optical limiting behavior. © 2005 Elsevier B.V. All rights reserved.Item Nonlinear optical studies of 1-3-diaryl-propenones containing 4-methylthiophenyl moieties(2007) John Kiran, A.; Mithun, A.; Shivarama Holla, B.; Shashikala, H.D.; Umesh, G.; Chandrasekharan, K.The third-order nonlinear optical properties of chalcone derivatives have been studied using the single beam Z-scan technique. The dependence of ?(3) on different donor and acceptor type substituents demonstrates the electronic nonlinearity of compounds. The largest value of nonlinear refractive index, n2, measured for a high electron donor substituted molecule is -2.033 × 10-11 esu. These molecules exhibit a strong two-photon absorption and interesting optical limiting of nanosecond laser pulses at 532 nm. © 2006 Elsevier B.V. All rights reserved.Item Third-order nonlinear optical studies of newly synthesized polyoxadiazoles containing 3,4-dialkoxythiophenes(2006) Udayakumar, D.; John Kiran, A.; Vasudeva Adhikari, A.V.; Chandrasekharan, K.; Umesh, G.; Shashikala, H.D.The third-order nonlinear optical properties of newly synthesized soluble polyoxadiazoles containing 3,4-dialkoxythiophenes were investigated by using Z-scan and degenerate four-wave mixing (DFWM) techniques. The measurements were performed at 532 nm with 7 ns pulses from a Nd:YAG laser. We found a good agreement between the values of ?(3) determined from both the experiments. Z-scan results indicate a negative nonlinear refractive index, n2, whose magnitude is of the order of 10-10 esu for all the copolymers. The variation of nonlinear response among the copolymers clearly indicates the dependence of ?(3) on donor and acceptor type of units present in these copolymers. The copolymers exhibit strong reverse saturable absorption and good optical limiting properties at 532 nm. © 2006 Elsevier B.V. All rights reserved.Item Nonlinear optical studies of a newly synthesized copolymer containing oxadiazole and substituted thiophenes(2007) John Kiran, A.; Udayakumar, D.; Chandrasekharan, K.; Ahdikari, A.V.; Shashikala, H.D.; Philip, R.We investigated the third-order nonlinear optical properties of a newly synthesized soluble copolymer containing oxadiazole and thiophene units using Z-scan and Degenerate Four Wave Mixing (DFWM) techniques. The measurements were performed at 532 nm with 7 ns pulses from a Nd:YAG laser. We found a good agreement between the values of ?(3) determined from both experiments. Z-scan results indicate a negative nonlinear refractive index, n2, whose magnitude is of the order of 10-10 esu. The copolymer exhibits strong nonlinear absorption and good optical limiting properties at 532 nm, and hence may be a potential material for optical limiting applications. © 2006 Elsevier B.V. All rights reserved.