<title>Holographic recording in amorphous semiconductor films</title>

Abstract

The present state of the real time holographic recording in amorphous semiconductor films is reviewed including mechanisms, parameters, properties and applications. Effects of the coherent, incoherent and relaxational self-enhancement as well as the influence of the film structure relaxation are considered. Quasi-permanent sub-band-gap light holographic recording is reported for the first time. Keywords: holography, amorphous semiconductor films, hologram self-enhancement, photoinduced phenomena. 282 SPIE Vol. 2968 • 0277-786X/971$1O.OO Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/25/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

Recording of holographic gratings and their coherent self-enhancement in an a-As₂S₃ film with a minimum light intensity modulation

“…Self-enhancement (SE) of a non-stationary hologram is an increase in its diffraction efficiency (DE) over time under the stimulus of a single beam light irradiation or simply in the dark [2,3].The SE effect was reported for the first time in 1973 by Gaylord et al [11] for phase holograms in LiNbO 3 :Fe crystals. Three types of SE can be distinguished: (i) coherent SE due to the holographic recording by diffracted waves; (ii) incoherent SE due to the contrast and/or transmission increase of a hologram by incoherent light; (iii) relaxational (or dark) SE due to the contrast and/or transmission increase of a hologram by thermostimulated relaxation processes [2,3].…”

“…Photosensitivity of these films depends on light intensity [17]. The existence of minimum visibility for the recording light intensity interference pattern could explain the fact that CSE is not observed in all materials as can be expected from the CSE complementary HG model [3,13] even when the holographic recording itself is efficient (Table 1). We have chosen an a-As 2 S 3 film for these experiments because the CSE effect is the most efficient in these films.…”

“…Three types of SE can be distinguished: (i) coherent SE due to the holographic recording by diffracted waves; (ii) incoherent SE due to the contrast and/or transmission increase of a hologram by incoherent light; (iii) relaxational (or dark) SE due to the contrast and/or transmission increase of a hologram by thermostimulated relaxation processes [2,3]. All three SE types can take place simultaneously.…”

“…Yet such studies at a fixed spatial frequency can be regarded as a special case of holographic grating spectroscopy of materials. The aim of this work was to study the recording light interference fringe visibility dependence of HG recording efficiency in an a-As 2 S 3 film by two beams (as usual) and by one beam in the process of HG coherent self-enhancement [2,3] focusing on extremely low visibilities.…”

“…Amorphous As 2 S 3 semiconductor chalcogenide films are used for real-time holographic information storage, optical computing, and for making holographic optical elements [2][3][4]. Diffraction efficiency exceeding 80% [4], high spatial resolution of spatial frequencies up to 9700 lines/mm [4,5], simplicity of a direct recording process for practically permanent holograms which need neither fixing nor development, reversibility, and availability of large samples are some of the attractive features of these materials.…”