Ferroelectrics, 320:149–152, 2005 Copyright © Taylor & Francis Inc. ISSN: 0015-0193 print / 1563-5112 online DOI: 10.1080/00150190590967008 Ferroelectric Based Pyroionization IR Converter F ˙ IL ˙ IZ KARA ¨ OMERL ˙ IO ˘ GLU 1,∗ AND AM ˙ IRULLAH MAMEDOV 1,2,∗∗ 1 Cukurova University, Faculty of Art & Science, Department of Physics, 01330, Balcali, Adana, Turkey 2 Harran University, Faculty of Art & Science, Department of Physics, 63200, Yenisehir, Sanlıurfa, Turkey The characteristics of a noncoherent–coherent IR image converter that uses pyroelectric effect in LiNbO 3 and the electro-optic effect and photorefraction in Bi 12 XO 20 (X = Ti, Si, Ge) has been analysed theoretically and experimentally. An experimental multilayered structure by which IR radiation can be converted into coherent visible radiation was obtained on the basis of theoretical calculations. The measured threshold sensitivity of the converter, ∼10 −5 W/cm 2 , was found to be comparable to theoretical estimates. The limiting resolution of the readout image was about 0.1 lp/mm. The change in the optical properties is estimated by use of the linear equation of an applied electric field (or polarization) that is not excessively strong. Keywords LiNbO 3 ; “light- light” converter 1. Introduction The development of modern systems for the optical handling of information requires the generation of new active elements with new properties and capabilities. To solve many problems in the parallel processing of information in the form of optical images “light- light” type converters are used. Such converters use the redistribution of current or field in the element due to a local change in the resistance of the layer from the photoelectric effect [1]. The principal restriction of existing converters is the limited spectral range of sensitivity. In this connection we have investigated the possibility of using a pyroelectric crystal as the active layer in “light- light” converters. Use of a pyroelectric crystal broad the spectral range of sensitivity of the converter into the far IR. The proposed pyroelectric converter is a synthesis of the “light- light” photoionization converter [1, 2] and the idea of Rosenblum [3] regarding the possibility of large electric fields developing in the gap between counterelectrode and pyroelectric with the rapid heating of the latter. It is completely free of the limitation of the photoionization converter [2] in the spectral range of sensitivity. Received September 6, 2004; In revised form December 21, 2004. ∗,∗∗ Corresponding authors. E-mails: filizk@cu.edu.tr; mamedov@cu.edu.tr [617]/149