Contents lists available at ScienceDirect Optical Materials journal homepage: www.elsevier.com/locate/optmat Spectral and third order nonlinear optical properties of Yttrium-doped BaWO 4 nanostructures K. Mani Rahulan a,∗ , R. Annie Sujatha a , N. Angeline Little Flower a , G. Vinitha b , Ayisha Suhana a a Nanophotonics Research Laboratory, Department of Physics & Nanotechnology, SRM Institute of Science & Technology, Kattankulathur, Chennai 603203, India b Division of Physics, School of Advanced Sciences, Vellore Institute of Technology, Chennai 600048, India ARTICLE INFO Keywords: Saturable absorption Yttrium Z-scan Nanostructures ABSTRACT BaWO 4 nanostructures doped with diferent concentrations of Yttrium have been synthesized by a chemical method. The as-prepared samples were characterized by UV–vis difuse refectance spectra, X-ray difraction, Fourier transform infrared spectroscopy, Transmission electron microscopy and Raman spectra. From the UV–vis spectra, it is seen that absorption band edge shifted towards the visible region upon Y doping. The X-ray dif- fraction and Raman analyses reveal that the BaWO 4 powders present a tetragonal structure. The third-order nonlinear optical responses of BaWO 4 nanostructures on the efect of Y concentrations was investigated by Z- scan technique using a continuous wave Nd:YAG laser at 532 nm. Experimental results have shown that the observed nonlinear absorption and nonlinear refraction behavior is attributed to saturable absorption and thermal nonlinear efects. 1. Introduction In recent years, the investigations on nonlinear optical (NLO) ma- terials with large optical nonlinearities and ultrafast response have re- ceived considerable interest for the development of next generation photonic devices, since these properties are essential for applications in optical signal processing, optical data storage, optical limiting and optical switching devices [1,2]. Therefore, over the years numerous materials have been discovered for use as NLO materials. In this regard, the Metal tungstates with formula MWO 4 based on the scheelite-type have attracted much interest due to its usage in electro-optic applica- tions such as solid-state laser and in optical fber applications [3]. Be- cause of its fascinating luminescence and structure properties, these materials have found to be an attractive material for photonics and photoelectronics. BaWO 4 is one of the important compound belong to alkaline-earth metal tungstate families having scheelite-structure. The essential properties of BaWO 4 can be tailored by loading suitable do- pants for desired applications. Advanced hybrid materials are needed with high NLO properties for next generation optical technologies. Recently, research on alkaline-earth metal tungstates have reported to be efcient luminescent hosts for rare earth metals [4,5]. Rare earth metal ions play a great role in advanced lighting systems and display felds due to the abundant emission colors based on their 4f-4f or 5d-4f transitions [6]. Extensive research has been made on rare earth ions doped materials, as these materials are potential candidates for applications like optical sensor (chemical sensor), lasers, optical am- plifers and as photonic or biophotonic devices [7,8]. Functionalization with rare earth ions can change the optical character of the host ma- terial. The advantage of this functionalization is that these materials ofer signifcant tunability of optical bandgap by changing their shape and size through the variation in the concentration of induced defect states leading to the display of exceptional properties. To date, much scientifc research has been interested in the synthesis of materials with controlled size and shape. Numerous synthesis approaches have been used for the preparation of barium tungstate (BaWO 4 ) nanostructures to achieve nanostructures with controlled size and shape, such as solid- state reaction [9], polymeric precursor method [10] precipitation method [11] hydrothermal [12], solvothermal [13]. Among all these methods, chemical precipitation technique presents signifcant ef- ciency particularly in the synthesis of rare earth doped materials, by this method the doped ions gets uniformly dispersed in the crystal lattice of the host. Although the structural and optical properties of the materials were exhaustively discussed, its third order NLO properties still remain unexplored. To the best of our knowledge, NLO properties of Y-doped BaWO 4 nanostructures are not yet discussed. Herein, we report the synthesis of Y-doped BaWO 4 nanostructures prepared by chemical method. The infuence of Y doping on the morphology and structure properties of BaWO 4 nanostructures was studied. Besides, the third order optical nonlinearities such as nonlinear refractive index and nonlinear absorption coefcient were investigated by a z-scan https://doi.org/10.1016/j.optmat.2018.12.014 Received 22 August 2018; Received in revised form 21 November 2018; Accepted 7 December 2018 ∗ Corresponding author. E-mail address: krahul.au@gmail.com (K. Mani Rahulan). Optical Materials 88 (2019) 466–471 Available online 24 December 2018 0925-3467/ © 2018 Elsevier B.V. All rights reserved. T