Linear and nonlinear optical properties of aligned elongated silver nanoparticles embedded in silica 35 X Linear and nonlinear optical properties of aligned elongated silver nanoparticles embedded in silica Raul Rangel-Rojo 1 , J.A. Reyes-Esqueda 2 , C. Torres-Torres 3 , A. Oliver 2 , L. Rodríguez-Fernandez 2 , A. Crespo-Sosa 2 , J.C. Cheang-Wong 2 , J. McCarthy 4 , H.T. Bookey 4 and A.K. Kar 4 1 Departamento de Optica, Centro de Investigación Científica y de Educación Superior de Ensenada, Apartado Postal 2732, Ensenada BC 22860, México. 2 Instituto de Física, Universidad Nacional Autónoma de México, Circuito de la Investigación Científica S/N, Ciudad Universitaria, Distrito Federal, México. 3 Sección de Estudios de Posgrado e Investigación ESIME-Zacatenco, Instituto Politécnico Nacional, México, D.F. 07738, Mexico 4 School of Engineering and Physical Sciences, David Brewster Building, Heriot-Watt University, Edinburgh, EH14 4AS, Scotland UK. 1. Introduction Nanoestructured materials have attracted a considerable amount of attention in the past few years for their potential use in different applications, especially in the field of optics. Because of this, the optical properties of semiconductor (Yildirim and Bulutay, 2008), organic (Kasai et al, 1992), and metallic nanoparticles embedded in different media, have been thoroughly studied. For metallic nanoparticles in particular, this has been driven by the possibility of the use of their nonlinear optical properties in information processing applications, and more recently for the potential implementation of plasmonic circuitry (Barnes et al, 2003; Maier et al, 2003). Regarding their nonlinear optical properties, metallic nanoparticles embedded in dielectric matrices have shown considerably large nonlinearities with response times in the picosecond regime (Inouye et al, 2000). One of the most important features of this class of materials is the possibility of tuning their optical properties by manipulation of the particle size, shape, and the appropriate choice of the host matrix, which has been explored to a certain extent. There are however few reports of the generation of elongated nanoparticles, and even fewer reports of the study of their linear and nonlinear optical properties (Kyoung & Lee, 1999; Elim et al, 2006; Ruda & Shirk, 2007; Lamarre et al, 2008). Among the many techniques employed to generate nanoparticles, metal ion implantation in glass substrates has proven to be a reliable technique for producing samples with well controlled characteristics. Recently, further high energy ion irradiation with different ions, has been shown to produce highly elongated metallic nanoparticles, with a prolate spheroidal shape (Oliver et al, 2006). Although the position of the nanoparticles produced 2