Micro-Raman spectroscopy investigation of the electron beam irradiation of LiNbO 3 surface for 2D photonic band gap grating inscription M.R. Beghoul a,d , A. Boudrioua a, * , R. Kremer a , M.D. Fontana a , B. Fougere b , C. Darraud b , J.C. Vareille b , P. Moretti c a Laboratoire Mate ´riaux Optiques, Photonique et Syste `mes (LMOPS), CNRS-UMR 7132, Universite ´ de Metz et Supe ´lec, 2, Rue E.Belin, 57070 Metz, France b Institut de Recherche XLIM, CNRS-UMR 6172, Universite ´ de Limoges, 123 Avenue A.Thomas 87060 Limoges, France c Laboratoire de Physico-Chimie des Mate ´riaux Luminescents (LPCML), CNRS-UMR 5620, Universite ´ Claude Bernard, Lyon I, France d Laboratoire d’Etudes des Mate ´riaux (LEM), Universite ´ de Jijel, Alge ´rie Received 5 May 2007; received in revised form 30 January 2008; accepted 5 February 2008 Available online 26 March 2008 Abstract We report the investigation of the physical phenomena which occur in LiNbO 3 during its surface irradiation by electron beam (EB) in order to fabricate 2D photonic band gap (PBG) grating. In order to better understand the mechanism of unusual holes formation by post-chemical etching, the induced micro structural modifications are studied by means of micro-Raman microscopy. We carried out EB bombardment on substrates of congruent z-cut lithium niobate. The main objective consists of the optimization of PBG grating fab- rication process for applications in the field of optical telecommunications. Ó 2008 Published by Elsevier B.V. Keywords: Photonic crystals; LiNbO 3 ; Micro-Raman; e-Beam 1. Introduction Progress in the field of photonics is undoubtedly deter- mined by the fabrication and the characterization of new materials able to be used to handle light. Moreover, the possibility of engineering these materials at the micro and nanometric scales makes it possible to adjust their linear and nonlinear optical properties to the applications consid- ered and thus to develop new optical components and optoelectronic devices to manipulate the photons. The sub-micrometer-structured materials called photonic band gap crystals (PBG) offer new prospects for light confine- ment and optical sources [1,2]. From the material point of view, photonic crystals were mainly realized in semiconductor materials [3–5] and very few teams throughout the world transposed their work on dielectric crystals in particular on ferroelectric ones. Accordingly, the use of materials such as lithium niobate as a photonic crystal could be of practical stake for pho- tonic technology. LiNbO 3 is a very important crystal [6] extensively used in many optoelectronic devices devoted to signal processing. For instance, the use of LiNbO 3 in its waveguide form has allowed in many cases to go beyond the limitations imposed by the use of bulk crystals [7,8]. The fabrication of 2D structures at sub-micrometer scale in LiNbO 3 has been recently reported by using sev- eral techniques such as scanning electron microscope (SEM) lithography [9], focused ion beam (FIB) milling [10], frustrated chemical etching induced by continuous wave or pulsed ultraviolet laser radiation [11–13], direct surface engineering by femtosecond laser irradiation [14], 0925-3467/$ - see front matter Ó 2008 Published by Elsevier B.V. doi:10.1016/j.optmat.2008.02.002 * Corresponding author. Present address: Laboratoire de Physique des Lasers, Institut Galile ´e – CNRS 7538, Universite ´ Paris 13, 99 Avenue Jean Baptiste Cle ´mont, F 93430 Villetaneuse. Tel.: +33 03 87 37 85 47; fax: +33 03 87 37 85 59. E-mail address: boudrioua@galilee.univ-paris13.fr (A. Boudrioua). www.elsevier.com/locate/optmat Available online at www.sciencedirect.com Optical Materials 31 (2008) 136–142