Faculty Publications

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Author: search.filters.author.Badekai Ramachandra, B.Subject: search.filters.subject.Z-scan

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    The ultrafast nonlinear optical response and multi-photon absorption of a new metal complex in the near-infrared spectral range
    (Institute of Physics Publishing, 2010) Kiran, A.J.; Lee, H.W.; Sampath Kumar, H.C.; Rudresha, B.J.; Badekai Ramachandra, B.; Yeom, D.-I.; Kim, K.; Rotermund, F.
    A new coordination compound, chloro(1,10-phenanthroline-N, N ?)(triphenylphosphine)copper(I) dichloromethane, incorporated in poly(methyl methacrylate) exhibits superior nonlinear optical properties in the near-infrared spectral region. Its nonlinear response time and third-order nonlinear optical susceptibility at 800nm are ? 90fs and 1.8 × 10 -10esu, respectively. Considerable nonlinear absorption is observed with this sample, near 800 and 1250nm. The contribution of the excited states to the total nonlinear absorption process is discussed. The results reveal the potential of this newly designed compound for multi-photon absorption-based photonic applications. © 2010 IOP Publishing Ltd.
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    Third-order optical nonlinear studies of Cobalt (II) Schiff base complex bearing triphenylphosphine using Differential Optical Kerr Gate and Z-scan studies
    (2010) Rudresha, B.J.; Badekai Ramachandra, B.; Ramakrishna, D.; Anthony, J.K.; Rotermund, F.
    The third-order optical nonlinearity of the composite film of coordination complex [CoLPPh3Cl] (L = N-(2-pyridyl)-N?-(salicylidene)hydrazine) and PMMA has been investigated by using Differential Optical Kerr Gate (DOKG) and Z-scan measurements. Large value of the third-order nonlinear optical susceptibility (?(3)) of the order of 10-10 esu was measured and its nonlinear response time was found to be faster than or comparable to the laser pulse width (90 fs) used. The single beam Z-scan technique was used to investigate the nonlinear absorption property of the composite near 800 nm. The sample exhibit saturable absorption. The nonlinear absorption coefficient of sample is found to be -32 cm/GW. © 2010 Elsevier B.V. All rights reserved.
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    Synthesis, characterization and third-order nonlinear optical studies of copper complexes containing 1,10-phenanthroline-5,6-dione and triphenylphosphine ligands
    (2011) Rudresha, B.J.; Badekai Ramachandra, B.; Sampath Kumar, H.C.; Shivakumar, K.I.; Safakath, K.; Philip, R.
    This research article describes the synthesis, characterization and third-order nonlinear optical studies of copper(I) complexes [Cu(Br)(N,N?-C12H6N2O2) (PPh3)] and [Cu(I)(N,N?-C12H6N 2O2)(PPh3)] abbreviated as [CuBrLPPh 3] (1) and [CuILPPh3] (2) (L = 1,10-phenanthroline-5,6- dione). Nonlinear optical properties of the complexes are investigated at 532 nm using single beam Z-scan and degenerate four-wave mixing (DFWM) techniques employing nanosecond laser pulses. The complexes show optical limiting behaviour due to "effective" two-photon absorption. The values of the effective two-photon absorption (2PA) coefficients (?), third-order nonlinear susceptibilities (?(3)), and figures of merit (F), are calculated. © 2010 Elsevier B.V. All rights reserved.
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    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.
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    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.
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    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.
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    Third-order nonlinear optical, optical power limiting, and all-optical switching studies on palladium complexes
    (2014) Manjunatha, K.B.; Shelar, V.M.; Dileep, R.; Umesh, G.; Satyanarayan, M.N.; Badekai Ramachandra, B.
    The authors report the third-order nonlinear optical properties of two palladium complexes in solution and film form using nanosecond Z-scan technique at 532 nm. The nonlinear refractive index n2of the investigated complexes is found to be negative. Both complexes exhibit strong reverse saturation absorption and show good optical power limiting of nanosecond pulses. Also the third-order nonlinear optical susceptibility of the complexes was determined using degenerate four-wave mixing technique. The variations of nonlinear response on donor and acceptor type of units present in the complexes are studied. The all-optical switching phenomenon was also demonstrated by using nanosecond pump-probe technique. © 2014 Copyright Taylor and Francis Group, LLC.
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    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.