Analysis of holographic data storage using a PA-LCoS device

Abstract

Holographic data storage systems (HDSS) have been a promising and very appealing technology since the first laser developments in the sixties. Impact of ongoing advances in the various components needs to be explored in its specific application to HDSS. In this sense, continuous progress is being produced in spatial light modulator (SLM) technology where parallel-addressed liquid crystal on silicon (PA-LCoS) microdisplays have replaced previous liquid-crystal displays (LCD) in most of optics and photonics applications. PA-LCoS microdisplays are well adapted to display phaseonly elements without coupled amplitude. In this paper, we analyse how PA-LCoS devices can also be used to display the widely applied binary intensity modulated (BIM) data pages. We also investigate hybrid-ternary modulated (HTM) data pages, which are very much demanding on the phase and amplitude modulation properties of an SLM. HTM data pages combine the ease of detection of BIM data pages, together with a large reduction of the DC term of the Fourier Transform of the data page. This reduction is necessary to avoid saturation of the recording material dynamic range. Simulated results show the magnitude of the expected DC term in the Fourier plane. We have verified the good performance of PA-LCoS to display BIM data pages. We have also obtained that pure HTM data pages cannot be produced with PA-LCoS devices, however, a rather close performance is obtained when implementing the pseudo-HTM data pages. In this work a more complete study of pseudo-HTM modulation is offered.