Electro-Optical Devices Obtained by LiNbO3 Crystals
Lithium niobate (LiNbO3) is a material of wide interest for both fundamental research and applications because of the richness of its physical properties. It is a ferroelectric, pyro-, and piezoelectric (PZ) material with large electrooptic (EO), acoustoo
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Electro-Optical Devices Obtained by LiNbO3 Crystals M. Paturzo, V. Pagliarulo, S. Grilli, and P. Ferraro
18.1 Introduction Lithium niobate (LN) is ferroelectric crystals of considerable interest in different fields of optics and optoelectronics. Due to its large values of the nonlinear optical, electro-optic (EO), piezoelectric and acousto-optical coefficients, LN is widely used for laser frequency conversion using the quasiphase matching (QPM) approach where the sign of nonlinearity has been periodically modulated by electric field poling (EFP). In the microwave and telecommunication field LN is used for surface acoustic devices and integrated optical modulators. Different LN based electrooptical devices are presented here and their possible application of an electro-optical tunable 2D hexagonal phase array in domain-engineered Z-cut lithium niobate crystal. In particular in Sect. 16.2 is shown how a such flexible array could be potentially used as a tunable lithographic mask. Section 18.2.1 concerns a new point-diffraction interferometer (PDI) based on a pinhole filter made by a z-cut LN crystal. The fabrication process and operating properties of such devices are shown and the advantages of the proposed PDI arrangement in respect of other configurations are discussed.
M. Paturzo (B) · V. Pagliarulo · S. Grilli · P. Ferraro Istituto Nazionale di Ottica del CNR (CNR-INO), Pozzuoli, Napoli, Italy e-mail: [email protected] V. Pagliarulo e-mail: [email protected] P. Ferraro 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_18, © Springer-Verlag Berlin Heidelberg 2014
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18.2 Tunable Two-Dimensional Hexagonal Phase Array in Domain-Engineered LN In this section is presented an electro-optic adaptive and dynamic hexagonal phase array fabricated in LN substrate that operates as a Talbot array illuminator (TAIL) [1]. Array illuminators are devices that transform a plane wave into a periodic optical intensity pattern. An important application of such devices is as spatially addressed multiplexing in optical telecommunications. In fact, in the fields of optical information processing, spatial light modulation (SLM) can be used to generate a dynamic array of light spots to address a spatial distribution of input ports of several communication channels (i.e. input fibre optical fibres). Different kinds of illuminator can be realized based on refractive, diffractive or hybrid configurations and different arrays can operate generating outputs in image plane [2]. As a consequence, some of the array illuminators, such as microlens arrays, generate outputs in image planes, some others operate in the Fourier regime, such as Dammann gratings [3] and others operate in the Fresnel regime as the TAIL that produces arrays of spots periodically arranged in the Fresnel plane [4]. Diffraction of a periodic object at distances, expressed as fractions of the Talbot distance, re
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