Full length article L-Lysine doped Oxalic acid single crystals – A potential phase matchable organic material for optical limiting applications J. Martin Sam Gnanaraj a , M. Iniya Pratheepa b , M. Lawrence b,⇑ a PG and Research Department of Physics, Government Arts College (Affiliated to Bharathidasan University), Tiruchirappalli 620 022, Tamil Nadu, India b Department of Physics, St. Joseph’s College (Autonomous), Tiruchirappalli 620 002, Tamil Nadu, India article info Article history: Received 11 January 2017 Received in revised form 19 December 2017 Accepted 29 May 2018 Available online xxxx Keywords: Organic crystal Optical limiting Phase matching Self-defocussing abstract L-Lysine doped Oxalic acid single crystals were grown by conventional slow evaporation solution growth technique. The unit cell dimensions were estimated by single crystal x-ray diffraction analysis. Spectral properties and functional groups of the title material were identified by FTIR spectral analysis. Linear optical characteristics of the material were examined by UV–Vis-NIR spectral analysis. The mechanical stability was assessed by Vicker’s hardness and it was observed that the load varies linearly with hard- ness value. Through NLO analysis the title material was found to be a phase matchable crystal. Third order nonlinear optical susceptibility of the material was tested by Z-scan technique and it was found to be in the order of 10 À6 esu. Optical limiting action of the sample at 532 nm was demonstrated using CW laser beam since the title material possesses self-defocussing effect. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction The nonlinear optical (NLO) materials capable of generating sec- ond harmonic have received a great deal of attention due to their commercial importance in the fields of optical communications, signal processing, sensing and instrumentation [1]. Organic mole- cules are capable of manipulating photonic signals efficiently are of importance in technologies such as optical computing and dynamic image processing [2]. Traditionally, crystals of organic materials have been grown from the melt [3,4], vapour [5] and solution [6,7]. The main advantage of solution growth method is convenience, simplicity and the possible avoidance of complex growth apparatus. The use of high purity solvent, solute and low viscosity of solution can give controlled supersaturation in growth. Organic molecules containing p-electron systems asymmetrized by the electron donor and acceptor groups are highly polarizable entities for nonlinear optical applications. This manuscript reports the synthesis, growth and characterization of one such organic crystal L-Lysine doped Oxalic acid, which was grown by conven- tional slow evaporation solution growth technique. The manu- script also highlights the linear and nonlinear optical properties of the as grown title material which could be used in nonlinear optical applications. 2. Synthesis and crystal growth Undoped Oxalic acid single crystals were grown by dissolving 1 mol% AR grade Oxalic acid (Merck 98%) in deionized water. The solution was stirred using magnetic stirrer at room temperature. The obtained salt of Oxalic acid was recrystallized several times in order to obtain crystals with good transparency. The grown crys- tals were harvested in 30 days. The same methodology was adopted for growing L-Lysine doped Oxalic Acid crystals. L-Lysine doped Oxalic acid crystals were grown by dissolving 1 mol% AR grade Oxalic acid (Merck 98%) and 0.5 mol% AR grade L-Lysine (Loba 97%) in deionized water. The contents were agitated vigorously using magnetic stirrer at room temperature for 3 h. A white salt of L-Lysine doped Oxalic acid was obtained which was recrystallized several times in order to obtain crystals with good transparency. The grown crystals were harvested in 30 days and the photograph of as grown L-Lysine doped Oxalic Acid crystal is shown in Fig. 1. 3. Characterization analysis The grown crystals were subjected to various characterization analysis in order to evaluate the structural, optical and mechanical properties of the crystal. The unit cell dimensions were analysed by ENRAF NONIOUS CAD4 X-Ray diffractometer equipped with MoKa radiation. The functional groups were identified using PERKIN ELMER FTIR within the wavenumber range of 400–4000 cm À1 . https://doi.org/10.1016/j.optlastec.2018.05.045 0030-3992/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Department of Physics, St. Joseph’s College, Tiruchirappalli 620 002, Tamil Nadu, India. E-mail address: drmlawrencelara@gmail.com (M. Lawrence). Optics and Laser Technology xxx (2018) xxx–xxx Contents lists available at ScienceDirect Optics and Laser Technology journal homepage: www.elsevier.com/locate/optlastec Please cite this article in press as: J.M.S. Gnanaraj et al., L-Lysine doped Oxalic acid single crystals – A potential phase matchable organic material for optical limiting applications, Opt. Laser Technol. (2018), https://doi.org/10.1016/j.optlastec.2018.05.045