Faculty Publications
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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 Nonlinear optical characterization of new thiophene-based conjugated polymers for photonic switching applications(2011) Hegde, P.K.; Vasudeva Adhikari, A.V.; Manjunatha, M.G.; Suchand Sandeep, C.S.S.; Philip, R.This research article describes a technique to synthesize new donor-acceptor-type conjugated polymers carrying 1,3,4-oxadiazolyl-naphthalene and 3,4-(ethylenedioxy/diphenyl)-thiophene moieties (P1 and P2) starting from 2,2?-sulfanediyldiacetic acid and diethyl ethanedioate through multistep reactions. The newly synthesized intermediates and the final polymers have been characterized by different spectroscopic techniques followed by elemental analysis. Their optical and electrochemical properties have been investigated by UV-visible, fluorescence spectroscopy, and cyclic voltammetric studies, respectively. Furthermore, the nonlinear optical transmission properties of these polymers have been investigated by the open aperture z-scan technique. The new polymers P1 and P2 have well-defined structures, good thermal stability, and band gaps of 1.98 and 1.88 eV, respectively. They emit bluish-green fluorescence both in solution and in film state. Interestingly, these polymers show saturable absorption behavior. The results of nonlinear optical studies reveal that they are potential candidates for photonic switching device applications. © 2011 Wiley Periodicals, Inc.Item Third order optical nonlinearity and optical limiting studies of propane hydrazides(Elsevier B.V., 2012) Naseema, K.; Manjunatha, K.B.; Sujith, K.V.; Umesh, G.; Kalluraya, B.; Rao, V.Four hydrazones, 2-(4-isobutylphenyl)-N?-[phenylmethylene] propanehydrazide (P1), 2-(4-isobutylphenyl)-N?-[(4- tolyl)methylene] propane hydrazide (P2), 2-(4-isobutylphenyl)- N?-[1-(4- chlorophenyl)ethylidene] propanehydrazide (P3) and 2-(4-isobutylphenyl)-N?-[1-(4-Nitrrophenyl)ethylidene] propane hydrazide (P4) were synthesized and their third order nonlinear optical properties have been investigated using a single beam Z-scan technique with nanosecond laser pulses at 532 nm. The measurement on the compound-P1 is not reported as there is no detectable nonlinear response. Open aperture data of the other three compounds indicate 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 values obtained are comparable with the values obtained for 4-methoxy chalcone derivatives and dibenzylideneacetone derivatives. The experimentally determined values of ?, n2, Re ?(3) and Im ?(3), ?h and ? of the compound-P4 are 1.42 cm/GW, -0.619 × 10-11 esu, -0.663 × 10-13 esu, 0.22 × 10-13 esu, 0.34 × 10-32 esu and 0.33 respectively. Further the compound-P4 exhibited the best optical power limiting behavior at 532 nm among the compounds studied. Our studies suggest that compounds P2, P3 and P4 are potential candidates for the optical device applications such as optical limiters and optical switches. © 2012 Elsevier B.V. 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 palladium(II) complex(2013) Manjunatha, K.B.; Dileep, R.; Umesh, G.; Badekai Ramachandra, B.Palladium complex with Schiff-base (PdL) was synthesized and composite films were fabricated on glass substrates by the spin coating technique. Z-scan and degenerate four wave mixing (DFWM) studies on the complex were performed using Q-switched Nd:YAG 7 ns laser pulses at 532 nm to reveal the third-order nonlinear optical (NLO) parameters. The third-order NLO susceptibility (?(3)) and second-order hyperpolarizability (?h) in film form are estimated to be of the order of 10-11 and 10 -30 esu respectively. Large nonlinear absorption (NLA) due to reverse-saturable absorption (RSA) in the complex exhibits good optical power limiting (OPL) performance. All-optical switching (AOS) experiments were performed using the pump-probe method. The Z-scan investigations reveal that the switching is caused by excited-state absorption (ESA) of the He-Ne laser. © 2013 Elsevier B.V.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 All optical nonlinear and switching characteristics of a novel ruthenium complex(Elsevier B.V., 2014) Manjunatha, K.B.; Dileep, R.; Umesh, G.; Satyanarayan, M.N.; Badekai Ramachandra, B.Third-order nonlinear optical properties of a novel ruthenium complex (2-thioxo-1,3-dithiole-4,5-dithiolato) triphenylarsenic Ru(III), have been investigated by employing Z-scan and DFWM techniques. The compound shows self-defocusing effect. Its nonlinear refractive index, third-order nonlinear optical susceptibility and the second-order hyperpolarizability are seen to be of the order of 10-9, 10-10 and 10-30 esu respectively. The nonlinear absorption coefficient is of the order of 10 -9 m/W. This material exhibits good optical power limiting capability which is seen to occur due to reverse saturable absorption. Experiments on all-optical switching action indicate that the sample can function as an optical inverter or a NOT gate. © 2014 Elsevier B.V. All rights reserved.Item All-optical switching and limiting properties of a Ru (II) Schiff-base complex for nonlinear optical applications(Institute of Physics Publishing michael.roberts@iop.org, 2017) Manjunatha, K.B.; Rajarao, R.; Umesh, G.; Badekai Ramachandra, B.R.; Poornesh, P.A salen-based ruthenium (Ru) (II) complex was synthesized for possible use in nonlinear optical device applications. The Ru complex was doped in a polymer matrix to fabricate films using a low-cost spin-coating technique. The third-order nonlinear optical parameters of the complex were investigated by Z-scan and degenerate four-wave mixing techniques. The study reveals two-order enhancement of third-order optical susceptibility ? (3) and exhibits superior limiting capability due to a reverse saturable absorption process. All-optical switching action for the films indicates that the sample can function as an optical inverter or a NOT gate. Hence, the Ru (II) Schiff-base complex materializes as a possible candidate for use in nonlinear optical devices. © 2017 Astro Ltd.Item High-Performance All-Optical Hybrid Plasmonic Switch Using Zn-Doped Cadmium Oxide(Institute of Electrical and Electronics Engineers Inc., 2023) Sahu, S.K.; Singh, M.In this article, a novel hybrid plasmonic waveguide (HPWG)-based all-optical switch (AOS) using zinc-doped cadmium oxide (ZnCdO) is reported and numerically investigated with the finite-element method. This oxide layer, which is a well-known transparent conductive oxide (TCO), can be switched from a dielectric to a metallic phase by electrical tuning the refractive index. The mobility of free-carrier concentration is highly magnified with a nonlinear optical effect induced by the epsilon-near-zero material near the telecommunication wavelength. We have simulated the plasmonic switch using the COMSOL Multiphysics simulator, predicting 13.75 dB extinction ratio (ER), 0.5 dB insertion loss (IL), and 27.5 figure-of-merit (FoM) at 1.55 \mu \text{m} wavelength. We also performed the reliability study by varying parameters, such as the width and height of the waveguide, which affect the performance of the on-chip switch design. In addition, the proposed AOS can be easily integrated with future silicon photonic circuits for ultrafast switching applications. © 1973-2012 IEEE.