Exploring binary and ternary modulations on a PA-LCoS device for holographic data storage in a PVA/AA photopolymer

Optical Modelling and Design IV

Fenoll

et al. 2016

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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.

Section: Introductionsupporting

confidence: 68%

Analysis of holographic data storage using a PA-LCoS device

Martínez-Guardiola

Optical Modelling and Design IV

Fenoll

et al. 2016

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“…In this work, and for simplicity, we have used a Binary Intensity Modulation (BIM) scheme 4 . We configured the PALCoS with an electrical configuration that offers a 180º retardance range, with good linearity, and allow us to obtain the maximum contrast and the less flicker possible, as we analyzed in [12].…”

Section: Characterization Methodsmentioning

confidence: 99%

“…In our HDSS we have used a PA-LCoS microdisplay as a data pager 3 . We have introduced it because we are interested in phase multilevel modulation schemes 4 . In this work we develop a characterization method that allows us to predict the performance by evaluating the limitations introduced by the elements in our optical system.…”

Section: Introductionmentioning

confidence: 99%

Anamorphic characterization of a PA-LCoS based holographic data storage system

Guardiola

Optics and Photonics for Information Processing XII

Estepa

et al. 2018

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We have included a Parallel Aligned Liquid Crystal on Silicon (PA-LCoS) microdisplay in a Holographic Data Storage System (HDSS). This novel display, widely accepted as Spatial Light Modulator (SLM), presents some advantages and disadvantages. One of these disadvantages is the anamorphic and frequency dependent effect. In this work we want to test this effect and see its effects in the complete optical process involved in the HDSS. We will use stripe-based patterns with different orientation (vertical and horizontal). To check the limits, we will increase the data density by decreasing the minimum stripe width. For evaluating the degradation suffered by the data page, we use the Bit Error Rate (BER) as figure of merit. We make a BER calculation from the statistical analysis of the histogram. In addition to the anamorphic effects we evaluate the degradation effects introduced by the non-uniformity in the illumination. To this goal we divide the image in several regions that are processed in the same way that the entire image. The error analysis of the entire optical system is useful for its calibration and fine adjustment. Once we have characterized the experimental setup we introduce the holographic material. Thus, by making the same analysis, we can evaluate the errors introduced by the material. As holographic material we use Polyvinyl Alcohol Acrylamide (PVA/AA), that has been characterized and developed in previous works by our group.

“…Flicker is a typical degradation effect in modern LCoS devices, especially in the digitally addressed [24][25] [26] [27] . These techniques had been applied to previous PA-LCoS in the visible as polarization conversors [28] , to display multilevel diffractive optical elements [29] and in holographic data storage systems [30] . In this work we demonstrate the applicability of these techniques to the telecommunications C-band illumination and to this novel smaller pixel size PA-LCoS devices.…”

Section: Introductionmentioning

confidence: 99%

Polarimetric and diffractive evaluation of 3.74 micron pixel-size LCoS in the telecommunications C-band

Wang

Martínez

Optics and Photonics for Information Processing XI

et al. 2017

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Liquid-crystal on Silicon (LCoS) microdisplays are one of the competing technologies to implement wavelength selective switches (WSS) for optical telecommunications. Last generation LCoS, with more than 4 megapixels, have decreased pixel size to values smaller than 4 microns, what increases interpixel cross-talk effects such as fringing-field. We proceed with an experimental evaluation of a 3.74 micron pixel size parallel-aligned LCoS (PA-LCoS) device. At 1550 nm, for the first time we use time-average Stokes polarimetry to measure the retardance and its flicker magnitude as a function of voltage. We also verify the effect of the antireflection coating when we try to characterize the PA-LCoS out of the designed interval for the AR coating. Some preliminary results for the performance for binary gratings are also given, where the decrease of modulation range with the increase in spatial frequency is shown, together with some residual polarization effects.