Synthesis, characterization and studies on the nonlinear optical parameters of hydrazones K. Naseema a , K.V Sujith b , K.B. Manjunatha c , Balakrishna Kalluraya b , G. Umesh c , Vijayalakshmi Rao a,n a Department of Materials Science, Mangalore University, Mangalagangothri-574199, India b Department of Chemistry, Mangalore University, Mangalagangothri-574199, India c Department of Physics, NITK, Surathkal, Mangalore-575025, India article info Article history: Received 11 August 2009 Received in revised form 12 November 2009 Accepted 16 November 2009 Keywords: Nonlinear optical properties Optical limiting Two photon absorption abstract Three hydrazones, 2-(4-methylphenoxy)-N 0 -[(1E)-(4-nitrophenyl)methylene]acetohydrazide (com- pound-1), 2-(4-methylphenoxy)-N 0 -[(1E)-(4-methylphenyl)methylene]acetohydrazide ((compound-2) and N 0 -{(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 n 2 , the nonlinear absorption coefficient b, the magnitude of the effective third order susceptibility w (3) , the second order hyperpolarizability g h and the coupling factor r 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. 1. Introduction In recent years, investigations into the nonlinear optical properties of different materials have attracted considerable attention, because they provide valuable information for the structural analysis of these materials and for their practical use in optoelectronic devices. Among a large number of materials with a pronounced nonlinear optical response, the compounds whose refractive indices change significantly with the intensity of light are of prime importance. This property provides a means of controlling the optical propagation in a medium. It is known that, for the most part, organic compounds with a strongly delocalized conjugate p-electron system possess the required property [1]. The design strategy, used by many with success, involves connecting donor and acceptor groups at the terminal position of a p bridge to create highly polarized molecules, which could exhibit large molecular nonlinearity. To date, the types of p bridges investigated for developing efficient NLO materials and molecules are D-Aolefines [2,3], acetylenes [4], azobridges [5], aromatic[6] and heteroaromatic rings [7,8]. Heterorings such as furan and thiophene, due to their relatively lower aromatic stabililization energy than benzene, are reported to provide more effective p-conjugation between D and A, resulting in larger nonlinearities [9]. Various aromatic donors and acceptors have been used to tune electronic factor and understand the origin of nonlinearity in these molecules. The phenomenon of optical power limiting, a nonlinear optical effect, has attracted much attention due to its application to the protection of eyes and sensitive optical devices from high power laser pulses. Since the discovery of the optical limiting phenom- enon, much work has been done in synthesizing new materials with adequate optical limiting property. The optical limiting behaviour resulting from nonlinear absorption can occur due to reverse saturable absorption, two photon absorption, nonlinear refraction and nonlinear scattering. Nonlinear optical properties observed in some materials such as semiconductors can be explained on the basis of two photon absorption, wherein the material absorbs two photons simulta- neously at higher light intensities [10]. Generally, optical limiting properties exhibited by organic molecules is related to high delocalization of the p-electrons. Excellent optical limiting responses have been reported in many phthalocyanines and their derivatives. They possess extensive two-dimensional p-electron delocalization and hence have been shown to be as promising NLO materials. In general, the presence of strong nonlinear absorption is good for limiting property, while the presence of strong nonlinear refraction facilitates optical switching property of organic ARTICLE IN PRESS Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/optlastec Optics & Laser Technology 0030-3992/$ - see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.optlastec.2009.11.019 n Corresponding author. Tel.: + 91 824 2287249. E-mail address: vijrao@yahoo.com (V. Rao). Please cite this article as: Naseema K, et al. Synthesis, characterization and studies on the nonlinear optical parameters of hydrazones. Opt Laser Technol (2009), doi:10.1016/j.optlastec.2009.11.019 Optics & Laser Technology ] (]]]]) ]]]–]]]