Applications of Oxide Nanomaterials in Nonlinear Optics
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Applications of Oxide Nanomaterials in Nonlinear Optics Reji Philip1,2,*, C.S. Suchand Sandeep1, R. Seema3, Shiji Krishnan3, Panit Chantharasupawong2, Nandakumar Kalarikkal3,4, Jayan Thomas2 1 2 3
Light and Matter Physics Group, Raman Research Institute, C.V. Raman Avenue, Sadashivanagar, Bangalore 560080, India. NanoScience Technology Center and CREOL, College of Optics and Photonics, University of Central Florida, Orlando, FL 32826, USA. School of Pure and Applied Physics and 4 Center for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam 686560, India.
ABSTRACT Nonlinear optical effects are revealed when strong light fields interact with matter. It has been shown that nanomaterials exhibit properties which are very different from the bulk, and in many cases, the nonlinear optical (NLO) efficiency of nanomaterials is found to be higher in comparison. Recently there has been substantial interest in developing novel NLO media for various applications. Even though several organic as well as inorganic materials have been studied in this connection, only a limited number of NLO reports exist for oxide nanomaterials. Therefore, in this paper we present results of NLO measurements recently conducted in our laboratory in three different oxide nanosystems. It is found that oxide nanomaterials are generally robust, and exhibit good NLO efficiencies, which make them potential candidates for photonic and optoelectronic applications. INTRODUCTION Nanomaterials are known to exhibit physical and chemical properties which are vastly different from those of the bulk state [1]. This behavior originates from factors associated with size reduction, such as increase in grain boundaries and enhanced surface to volume ratios. Nanostructuring of semiconductor, metallic, or oxide crystals is found to enhance their optical nonlinearity. In the past few years there has been substantial interest in the development of NLO media based on nanomaterials. To elucidate the suitability and applicability of oxide nanoparticles in NLO, in this work we discuss NLO results recently measured in our lab in the following materials: the blue phosphor Strontium Cerate (Sr2CeO4) [2], multiferroic Yttrium Chromite (YCrO3) [3], and mixed zinc ferrites [4]. It is shown that these materials exhibit an optical limiting property when excited in the visible spectral region using nanosecond laser pulses. EXPERIMENTAL DETAILS For the present measurements we employed the technique of open aperture Z-scan [5], which is widely used for estimating nonlinear absorption coefficients of materials. An Nd:YAG laser (Minilite I, Continuum) emitting 5 ns laser pulses at 532 nm, operated in the range of 100 to 300 microjoules pulse energy, was used as the excitation source. In the open aperture Z-scan the laser beam is focused using a lens, and the sample transmission is measured as a function of the sample’s relative position with respect to the beam focus (z=0).
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A plano-convex lens (f=200 mm) was used for focusing the laser beam, and the beam diamet
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