Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
12 results
Search Results
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 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.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 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 Study of third-order nonlinear optical and all-optical switching properties of palladium metal-organic complex(Elsevier B.V., 2013) Manjunatha, K.B.; Ramakrishna, R.; Umesh, G.; Badekai Ramachandra, B.We report the results of studies on third-order nonlinear optical properties of a newly synthesized palladium metal-organic complex [PdLPPh 3] (L = N-(2-pyridyl)-N?-(5-chlorosalicylidene)hydrazine) both in film and solution form using Z-scan and degenerate four wave mixing (DFWM) techniques. Experiments were performed using Q-switched Nd: YAG laser with nanosecond pulses at 532 nm. Investigations revealed that the palladium metal-organic complex possesses nonlinear absorption coefficient ?eff which is of the order of 10-9 m/W due to reverse saturable absorption (RSA) and negative nonlinear refractive index (self-defocusing) n2 which is of the order of 10-9 esu. The real and imaginary parts of the third-order nonlinear optical susceptibility (?(3)) were found to be of the order of 10-11 esu. The second-order hyperpolarizability (?h) was estimated to be of the order of 10-30 esu. The results of pump-probe experiments show that the switch-on and switch-off times of the palladium metal-organic complex were in ?s for different pump intensities and the energy dependent transmission studies reveal better limiting property of the compound at nanosecond regime. Thus the nonlinear response of the material suggests that it has a potential application for high sensitive photonic devices. © 2013 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 Investigation of third-order nonlinear and optical power limiting properties of terphenyl derivatives(2014) Kamath, L.; Manjunatha, K.B.; Shettigar, S.; Umesh, G.; Narayana, B.; Samshuddin, S.; Sarojini, B.K.A series of new chalcones containing terphenyl as a core and with different functional groups has been successfully synthesized by Claisen-Schmidt condensation method in search of new nonlinear optical (NLO) materials. Molecular structural characterization for the compounds was achieved by FTIR and single crystal X-ray diffraction. The third-order NLO absorption and refraction coefficients were simultaneously determined by Z-scan technique. The measurements were performed at 532 nm with 7 ns laser pulses using a Nd:YAG laser in solution form. The Z-scan experiments reveal that the compounds exhibit strong nonlinear refraction coefficient of the order 10-11 esu and the molecular two photon absorption cross section is 10-46 cm 4 s/photon. The results also show that the structures of the compounds have great impact on NLO properties. The compounds show optical power limiting behavior due to two-photon absorption (TPA). © 2013 Elsevier Ltd.