Faculty Publications
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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 Third-order nonlinear optical properties and optical switching of palladium (I) complex(2011) Manjunatha, K.B.; Dileep, R.; Shelar, M.S.; Umesh, G.; Satyanarayan, M.N.; Badekai Ramachandra, B.R.We report the third-order nonlinear optical, optical power limiting and optical switching study of palladium-N-(2-pyridyl)-N′- (5-amino salicylidene) hydrazine triphenylphosphine, using Z-scan technique and pump-probe technique. The measured nonlinear refractive index is n 2=-6.022×10-9esu. The complex exhibits the reverse saturable absorption (RSA), the nonlinear absorption coefficient of β=10.748×10-9m/W. The good optical power limiting and optical switching behavior were observed in this complex. These suggest that this complex is a potential molecule for photonic applications. © 2011 American Institute of Physics.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 Synthesis, growth and characterization of 1-(5-chlorothiophen-2-yl)-3-(2,4, 5-trimethoxyphenyl) prop-2-en-1-one single crystal: A potential NLO material(2011) Prabhu, A.N.; Upadhyaya, V.; Arasalike, A.; Maddasani, M.; Manjunatha, K.B.; Umesh, G.A potentially useful nonlinear optical (NLO) organic material, 1-(5-chlorothiophen-2-yl)-3-(24,5-trimethoxyphenyl)prop-2-en-1-one(CTTMP), has been synthesized and grown as a high-quality single crystal by the slow evaporation technique. The grown crystals were characterized by UV-visible spectroscopy. The material has thermal stability up to its melting point. Single beam Z-scan technique was employed to study the third order NLO properties of the material. © 2011 American Institute of Physics.Item Investigation of nonlinear optical and all-optical switching properties of novel ruthenium complex(IEEE Computer Society help@computer.org, 2012) Manjunatha, K.B.; Shettigar, S.; Rajarao, R.; Umesh, G.; Badekai Ramachandra, B.The nonlinear optical, optical limiting and all-optical switching properties of novel ruthenium complex doped PMMA film were investigated at 532 nm. The investigations show that the complex is a potential molecule for photonic applications. © 2012 OSA.Item Investigation of Nonlinear Optical and All-Optical Switching Properties of Novel Ruthenium Complex(Optica Publishing Group (formerly OSA), 2012) Manjunatha, K.B.; Shettigara, S.; Rajarao, R.; Umesh, G.; Badekai Ramachandra, B.The nonlinear optical, optical limiting and all-optical switching properties of novel ruthenium complex doped PMMA film were investigated at 532 nm. The investigations show that the complex is a potential molecule for photonic applications. © 2012 OSA - The Optical Society. All rights reserved.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 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 Studies on third-order nonlinear optical properties and reverse saturable absorption in polythiophene/poly (methylmethacrylate) composites(Springer Verlag, 2009) Poornesh, P.; Umesh, G.; Hegde, P.K.; Manjunatha, M.G.; Manjunatha, K.B.; Vasudeva Adhikari, A.V.We report here the studies on third-order nonlinear optical properties of two novel polythiophene composite films investigated using the Z-scan technique. The measurements were carried out using a Q-switched, frequency doubled Nd:YAG laser producing 7 nanosecond laser pulses at 532 nm. Z-scan results reveal that the composite films exhibit self-defocusing nonlinearity. The real and imaginary parts of the third-order nonlinear optical susceptibility were of the order 10-12 esu. 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). The polythiophene composite films also exhibit good optical power limiting of the nanosecond laser pulses. The nonlinear optical parameters are found to increase on increasing the strength of the electron-donor group, indicating the dependence of ? (3) on the electron-donor/acceptor units of polythiophenes. © 2009 Springer-Verlag.