Evaluation of nonlinear optical parameters of TiN/PVA nanocomposite e A comparison between semi empirical relation and Z-Scan results S. Divya * , V.P.N. Nampoori, P. Radhakrishnan, A. Mujeeb International School of Photonics, Cochin University of Science and Technology, Cochin, Kerala 682022, India article info Article history: Received 17 May 2013 Received in revised form 2 September 2013 Accepted 12 October 2013 Available online 24 October 2013 Keywords: WempleeDi Domenico (WDD) single oscillator model Miller’s rule Nonlinear optical properties Z-Scan abstract We report on the third order non linearity of TiN/PVA nanocomposites. Linear and nonlinear optical properties were studied from theoretical and experimental method. Theoretical method involved Tichy and Ticha relation pooled with generalised Miller’s rule. During the study dispersion of refractive index is analysed using the WempleeDi Domenico single oscillator model. Z-Scan was used as the experimental tool. The results derived from theoretical method deviated greatly from the experimental .We believe that such incongruity is due to the SPR property of the TiN nanoparticle whose SPR peak almost coincides with the irradiated laser wavelength. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Nonlinear optical effects have an important role in modern photonics technology which includes generation of ultra-short technology pulses, ultrafast switching, controlling the frequency spectrum of laser light, all-optical signal processing [1]. The suit- ability of a material for these device applications requires a large magnitude of the third-order nonlinear optical susceptibility. Op- tical nonlinearities are fundamentally weak, as they are governed by photonephoton interactions enabled by materials though it can be strengthened in material environments that provide mecha- nisms for field enhancement. Such an increased effective nonlinear optical response can be achieved through plasmonic effects. Such effects arise from coherent oscillations of conduction electrons near the surface of noble metal structures [2,3]. Actually, a few other elements are also possible candidates for such devices like nano- spheres of lithium, potassium and sodium etc. [4,5]. Recent studies have proved that TiN can also be considered a possible material for plasmonic devices [6,7]. Unlike conventional plasmonic materials like Gold and Silver, TiN is much more robust to the losses at optical frequencies. Cortie et al. has reported detailed study on the merits of TiN as a plasmonic material [7]. The resonance frequency of surface plasmons depends on the parameters such as nanoparticle morphology, concentration, and dielectric constant of the host where the nanoparticles are embedded. These nanoparticles when embedded in a suitable dielectric host matrix, they achieve better stability compared to a colloidal solution [8]. If the dielectric matrix hence used offers the ease of flexibility, like production of free standing films, which can be mechanically manipulated for device applications then it is an additional advantage. Apart from this, the incorporation of nanoparticles in a polymer matrix is found to change the optical properties of both materials [9e11]. From a device point of view, polymer nanocomposites have found many potential applications in the fields of optics, electrics, mechanics, and photoconductors. Polyvinyl Alcohol (PVA) is one such polymer which has recently been demonstrated to be a useful alternative to the bulk polymer, as its high surface area and mechanical proper- ties are interesting for various applications [12,13]. In this paper we report a comparative evaluation on the optical characterization of TiN/PVA composites deduced from Z-Scan Experiment as well as from the theoretical method entailing Tichy and Ticha relation pooled with Miller’s generalized rule [14]. Sim- ple semi-empirical relation based on generalized Miller’s rule al- lows an estimation of nonlinear susceptibility (c (3) ) and non-linear refractive index (n 2 ) from linear refractive index and from the dispersion energy and effective oscillator energy of the WempleeDi Domenico model. Z-Scan is one of the simpler experimental * Corresponding author. E-mail address: divyasasi7@gmail.com (S. Divya). Contents lists available at ScienceDirect Current Applied Physics journal homepage: www.elsevier.com/locate/cap 1567-1739/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cap.2013.10.011 Current Applied Physics 14 (2014) 93e98