Photonic Bandgap Properties of Lithium Niobate
The development of all-optical, acousto-optical or electro-optical photonic crystals (PhCs) represents a stimulating challenge for the production of advanced functionalities in compact optical devices. LiNbO3 appears as an excellent candidate for such rea
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Photonic Bandgap Properties of Lithium Niobate N. Courjal, F.I. Baida, M.-P. Bernal, J. Dahdah, C. Guyot, H. Lu, B. Sadani, and G. Ulliac
12.1 Introduction Because of their compact, essentially chip-scale sizes, photonic crystals (PhCs) have been attracting considerable theoretical and experimental attention [1] for the last decades. They have applications in fields ranging from fundamental physics to telecommunications systems. Commercial products involving PhCs are now available in the form of sensors [2]. Photonic crystals are periodic structures that are designed to affect the motion of photons in a similar way that periodicity of a semiconductor crystal affects the behavior of electrons. The non-existence of propagating electromagnetic modes inside the structures at certain frequencies introduces unique optical phenomena such as low-loss-waveguides, omni-directional mirrors and others. The part of the spectrum for which wave propagation is not possible is called the photonic bandgap (PBG). The underlying physical phenomenon is based on diffraction. Therefore, the lattice constant of the photonic crystal structure is in the same length-scale as half the wavelength of the electromagnetic wave. The fabrication of these PhCs on materials that are strongly sensitive to external stimuli (electric field, temperature. . . ) is a key step towards practical PhC-based optical processing devices. Several approaches have been proposed and demonstrated for the realization of such compact devices. One of them consists in infiltrating passive materials with liquid crystals [3]. An alternative method relies on the processing of active materials like semi-conductors which may be driven by modulation of the injection current [4]. Amongst the optically tunable materials, lithium niobate appears as a promising candidate, due to its high electro-optical, acousto-optical, and non-linear optical coefficients. In addition, the material has optical transparency with an ultra-high N. Courjal · F.I. Baida · M.-P. Bernal (B) · J. Dahdah · C. Guyot · H. Lu · B. Sadani · G. Ulliac Département d’Optique P.-M. Duffieux, Institut FEMTO-ST, CNRS UMR 6174, Université de Franche-Comté, Besancon, France e-mail: [email protected] P. Ferraro et al. (eds.), Ferroelectric Crystals for Photonic Applications, Springer Series in Materials Science 91, DOI 10.1007/978-3-642-41086-4_12, © Springer-Verlag Berlin Heidelberg 2014
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bandwidth that spans from 350 nm to 5200 nm. In 2000, Broderick et al. reported the first nonlinear 2D PhC, and demonstrated efficient quasi-phase-matched 2nd harmonic generation by use of ferroelectric domain inversion [5]. More recently, electro-optic [6], acousto-optic [7] or pyroelectric 2D LiNbO3 PhCs [8] have also been realized in ultracompact devices. Here we describe the basic principles of such ultra-compact components, with a particular emphasis on electro-optic phenomena. The chapter is organized as follows. Firstly, we are going to describe in Sect. 12.2 which configurations
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