Holographic Optical Data Storage Research Articles

Exploring isotropic tendency for the blue membrane containing wild-type bacteriorhodopsin

Bacteriorhodopsin of purple membrane has wide potential applications in bioelectronics and biophotonic nanodevices. Upon acidification, it turns blue and upon further acidification by HCl, it retains its purple color. The acid-induced structural changes might be correlated to its crystalline structure, which might be mediated by lipids of purple membrane. Therefore, the present study aims at revealing the acidic pH dependence of anisotropic properties of bacteriorhodopsin. The electric impedance has been measured for parallel- and perpendicular-oriented purple membrane, in addition to the randomly-oriented one in the acidic pH range. The results have showed that the electric anisotropy is proportional to the color transitions occurred at low pH with consistent pKa values. It has found that the bacteriorhodopsin, upon turning into blue form, tends to be isotropic within narrow pH region around 2.55, whereas it preserves its anisotropy in its purple form. It is noteworthy that several mutants of bacteriorhodopsin that resemble its blue form became attractive in technical applications such as real-time holographic interferometry and optical data storage. Accordingly, such isotropic tendency might implicate bacteriorhodopsin for further potential technical applications.

Metasurface Holography in the Microwave Regime

Hologram technology has attracted a great deal of interest in a wide range of optical fields owing to its potential use in future optical applications, such as holographic imaging and optical data storage. Although there have been considerable efforts to develop holographic technologies using conventional optics, critical issues still hinder their future development. A metasurface, as an emerging multifunctional device, can manipulate the phase, magnitude, polarization and resonance properties of electromagnetic fields within a sub-wavelength scale, opening up an alternative for a compact holographic structure and high imaging quality. In this review paper, we first introduce the development history of holographic imaging and metasurfaces, and demonstrate some applications of metasurface holography in the field of optics. We then summarize the latest developments in holographic imaging in the microwave regime. These functionalities include phase- and amplitude-based design, polarization multiplexing, wavelength multiplexing, spatial asymmetric propagation, and a reconfigurable mechanism. Finally, we conclude briefly on this rapidly developing research field and present some outlooks for the near future.

Optical holographic data storage—The time for new development

The development of optical holographic data storage technology in the past 50 years is reviewed in this paper. With the continuous development of key devices and materials, optical holographic data storage technology is becoming more and more mature. At present, in the era of Big Data, the demands for data storage density and data transfer rate are greater than ever before. Optical holographic data storage has become a potential candidate for the next generation of data storage technology because of its advantages of superhigh storage capacity, superfast data transfer rate, and superlong storage life. The coaxial holographic storage system will become the cornerstone of further practicality of holographic storage technology because of its compact structure, simple operation and strong compatibility. Meanwhile, new phase modulated holographic data storage system is becoming the research hotspot. The new round of rapid development has arrived.

Recent advances in metasurface hologram technologies (Invited paper)

Since Leith and Upatnieks demonstrated the first optical hologram in 1964, hologram technology has attracted a great deal of interest in a wide range of optical fields owing to its potential use in future optical applications such as holographic imaging and optical data storage. Although there have been considerable efforts to develop holographic technologies using conventional optics, critical issues still hinder future development. Recently, metasurfaces composed of artificially fabricated subwavelength structures have been considered as novel holographic devices that show an unprecedented ability to control electromagnetic waves. In this review, we outline the recent progress in metasurface holography. A general introduction to several types of metasurface holography categorized based on their physics and application is provided. Then, our personal perspective on the future of this field is discussed.

Anamorphic and Local Characterization of a Holographic Data Storage System with a Liquid-Crystal on Silicon Microdisplay as Data Pager

In this paper, we present a method to characterize a complete optical Holographic Data Storage System (HDSS), where we identify the elements that limit the capacity to register and restore the information introduced by means of a Liquid Cristal on Silicon (LCoS) microdisplay as the data pager. In the literature, it has been shown that LCoS exhibits an anamorphic and frequency dependent effect when periodic optical elements are addressed to LCoS microdisplays in diffractive optics applications. We tested whether this effect is still relevant in the application to HDSS, where non-periodic binary elements are applied, as it is the case in binary data pages codified by Binary Intensity Modulation (BIM). To test the limits in storage data density and in spatial bandwidth of the HDSS, we used anamorphic patterns with different resolutions. We analyzed the performance of the microdisplay in situ using figures of merit adapted to HDSS. A local characterization across the aperture of the system was also demonstrated with our proposed methodology, which results in an estimation of the illumination uniformity and the contrast generated by the LCoS. We show the extent of the increase in the Bit Error Rate (BER) when introducing a photopolymer as the recording material, thus all the important elements in a HDSS are considered in the characterization methodology demonstrated in this paper.

Holographic Data Storage and Display by PANDA Ring Resonator Technique <sup></sup>

In this paper, a novel method of holographic data storage and display was demonstrated. The use of nonlinear optical device called PANDA ring resonator is realized by Whispering Gallery Mode (WGM) and manipulated by Phase Conjugate Mirror (PCM) techniques. The result shown that the proposed model was performed a 3x3 optical waveguide holographic matrix which manipulated with a various wavelength and can be well applied to dynamic holographic optical data storage, holographic display, and other applications by compact nonlinear optical device.

Co-doping with polysquaraine enhances the holographic optical data storage of PMMA/PQ photopolymers

In this study, we synthesised poly(3-octylpyrrole-co-squaric acid) (PSQ3), a polysquaraine, through the reaction of 3-octylpyrrole and squaric acid, and then co-doped it with phenanthrenequinone (PQ) into poly(methyl methacrylate) (PMMA) to improve the holographic data storage characteristics of the photopolymer. The photopolymers co-doped with relatively small amounts of PSQ3 exhibited greatly improved holographic recording characteristics, including superior diffraction efficiency and dynamic range (M#). Among the samples co-doped with PQ and PSQ3, the maximum diffraction efficiency reached 54.8% (cf. 9.0% for PMMA/PQ) without further downgrade and the value of M# reached 1.05 (cf. 0.46 for PMMA/PQ). Therefore, the holographic data storage characteristics of the photopolymer PMMA/PQ were improved through co-doping with PSQ3.

Sudan IV dye based poly(alkyloxymethacrylate) films for optical data storage

The polymer poly{1-[2′-methyl-4′-(2″-methylphenylazo) phenylazo]-2-(m-methacryloyloxyoctyloxy}naphthalene, where m=6, 8, 10, is synthesized by free radical addition polymerization method for holographic optical data storage. Characterization of the polymers is done by formation of the holographic grating. A study of the dependence of diffraction efficiency of the grating formed on various parameters is presented. Surface relief gratings on these polymer films are created upon exposure to argon ion laser beams at 514.5nm without any subsequent processing steps. The surface structure of the relief gratings has been investigated by atomic force microscopy. The depth of surface relief in a typical case is found to be around 40nm.

Investigation on effect of methylene spacer in holographic grating formation in eosin containing polymethacrylates

A new series of eosin dye based poly(alkyloxymethacrylate)s was synthesized with an even number of side-chain methylene spacers by a free radical addition polymerization method for holographic optical data storage applications. These polymers were characterized by UV, IR and 1H NMR spectroscopy. The glass transition temperature and thermal stability of the polymers were investigated by DSC and TGA, respectively. As the spacer length increases in the side-chain, Tg, Tm and thermal stability of the polymers decrease, while a reverse trend was observed with film forming ability of the polymers. The optical characterization of the polymers was investigated by forming holographic grating using an Argon ion laser. The grating diffraction efficiency was found to depend not only on the concentration of polymeric film but also on the spacer length of the polymers.

Polarization holographic high-density optical data storage in bacteriorhodopsin film

Optical films containing the genetic variant bacteriorhodopsin BR-D96N were experimentally studied in view of their properties as media for holographic storage. Different polarization recording schemes were tested and compared. The influence of the polarization states of the recording and readout waves on the retrieved diffractive image's intensity and its signal-to-noise ratio were analyzed. The experimental results showed that, compared with the other tested polarization relations during holographic recording, the discrimination between the polarization states of diffracted and scattered light is optimized with orthogonal circular polarization of the recording beams, and thus a high signal-to-noise ratio and a high diffraction efficiency are obtained. Using a He-Ne laser (633 nm, 3 mW) for recording and readout, a spatial light modulator as a data input element, and a 2D-CCD sensor for data capture in a Fourier transform holographic setup, a storage density of 2 x 10(8) bits/cm2 was obtained on a 60 x 42 microm2 area in the BR-D96N film. The readout of encoded binary data was possible with a zero-error rate at the tested storage density.

Experimental study on polarization holographic high density optical data storage with bacteriorhodopsin film

Genetic mutant bacteriorhodopsin BR_D96N film was experimentally studied on its holographic storage properties with different polarization recording waves. The influences of the different polarization states of the recording and readout wav es on the retrieval diffractive image's intensity and signal_to_noise_ratio were compared with each other. The experimental results showed that compared with ot her polarization holographic recording, orthogonal circular polarization recordi ng can realize the separation of the polarization state of the diffractive wave from the scattering noise, and thus has high signal_to_noise_ratio as well as hi gh diffraction efficiency. Using He_Ne laser (633nm, 3mW) as recording and reado ut beam, spatial light modulator as data input element and CCD as data capture e lement, orthogonal circular polarization holographic optical data storage was ma de on 60μm×42μm area of the BR_D96N film by Fourier transform holographic met hod. The area density of 2×108bit/cm2 was obtained, and t he encoded data was retrieved without errors.

Biological nano-ceramic materials for holographic data storage

New Retinal nano-ceramic materials with pillared hybrid micro-structures are fabricated for potential applications in optical holographic data storage. We observe that the Schiff bases have substantial effect on optical properties of Retinal nano-ceramic films as well as temporal response and diffraction efficiency for holographic storage. These inexpensive synthetic biological nano-ceramic thin films are good candidates for holographic storage and offer a simple procedure to solve the problems of volatility of optical storage in Retinal proteins. In addition, our study indicates feasibility of optimizing optical properties of nano-ceramic clay systems using Schiff bases for a variety of photonic applications.

Miniaturized volume holographic optical data storage and correlation system with a storage density of 10 Gb/cm3

The general idea of holographic optical data storage (HODS) is briefly introduced. Based on the recent advances of HODS, the key techniques and the challenges of HODS are discussed. Some new techniques are proposed to improve the system. A miniaturized volume holographic data storage and correlation system is presented. It can achieve a density of 10 Gb/cm3 and a fast correlation recognition rate of more than 2000 images per second. It shows the attracting potential advantages over other conventional storage methods in the information storage as well as information processing.

Miniaturized volume holographic optical data storage and correlation system with a storage density of 10 Gb/cm3

Miniaturized volume holographic optical data storage and correlation system with a storage density of 10 Gb/cm3

Diffusional enhancement of holograms: phenanthrenequinone in polycarbonate

As a further development of the manufacture of holographic gratings by the diffusion of phenanthrenequinone in polymer glass, the traditionally employed poly(methyl methacrylate) is replaced by poly(bisphenol-A-carbonate). The post-exposure growth and decay of the gratings in the two materials are compared at different spatial periods and temperatures. The medium with polycarbonate demonstrates a fortunate combination of significantly improved stability of the gratings and their faster development. Our results indicate that the polycarbonate materials promise to be suitable media for holographic optical elements and data storage.

Improving holographic data storage by use of an optimized phase mask

A method for improving the spectral distribution and for reducing the reconstruction error in optical holographic data storage is proposed. By use of an optimized phase mask in the input plane, the uniformity of the spectral distribution is optimized and the reconstruction error minimized. The phase mask is designed by use of amplitude-phase retrieval algorithms. Simulation results show the merits of the proposed method.

Spectroscopic studies of Mn^4+ ions in yttrium orthoaluminate

The absorption and emission spectra and the luminescence kinetics of Mn4+:YAlO3, the potential crystal for holographic recording and optical data storage, were studied at room and liquid-nitrogen temperatures. The spectroscopic properties of Mn:YAlO3 were compared with those of Mn:GdAlO3,Mn:Y3Al5O12, and Cr:YAlO3. It was found that a single-site occupancy of Mn4+ ions in YAlO3 and GdAlO3 at room temperature changes to a multisite occupancy at low temperature. Possible reasons for such a transformation are discussed. The parameters Dq and B in Mn4+:YAlO3 were determined to be 2115 and 680 cm-1, correspondingly.

Two-color holography in reduced near-stoichiometric lithium niobate

We explored a number of factors affecting the properties relevant to holographic optical data storage by using a two-color recording scheme in reduced, near-stoichiometric lithium niobate. Two-color, or photon-gated, recording is achieved by use of 852-nm information-carrying beams and 488-nm gating light. Readout at 852 nm is nondestructive, with a gating ratio of ~10(4). Recording sensitivity, gating ratio, dynamic range, and dark decay were measured for crystals of differing stoichiometry, degree of reduction, wavelength of the gating light, temperature, and optical power density. The two-color sensitivity per incident photon is still somewhat less than that of the one-color process at 488 nm for ~1 W/cm(2) of gating light but is essentially the same in terms of absorbed photons. Two-color recording is an attractive way of achieving nondestructive readout in a read-write material, and it allows selective optical erasure.

Effects of cross talk on fidelity in page-oriented volume holographic optical data storage

Using numerical simulation, we quantitatively examine the effects of cross talk on the recall fidelity of stored binary data in a page-oriented volume holographic memory system. We discuss the trade-off between the signal-to-noise ratio of the reconstructed bits and the optical throughput of the system (i.e., the fraction of the incident beam that is diffracted to the detector plane). We show that significant gains in the signal-to-noise ratio can be achieved with modest decreases in optical throughput in the region where the highest throughput occurs. The magnitude of this trade-off is influenced by both beam degeneracy and coherent recording cross talk. At low optical throughputs an upper limit to the signal-to-noise ratio is set by the cross talk caused by angular sidelobe overlap, which in turn is a function of the angular isolation of the angularly multiplexed data pages.

Optical memories implemented with photorefractive media

We consider holographic optical data storage systems implemented with photorefractive media. Our viewpoint emphasizes the close interaction between materials and device issues. First we discuss our current understanding of photorefractive physics as it pertains to the holographic data storage problem. Then we consider architecture issues, including angular, phase-encoded, and wavelength-multiplexing techniques, and several approaches to increasing the signal-to-noise ratio of the recordings. Finally, we discuss materials issues related to crystal growth and how crystal quality impacts the performance of data storage systems. Both bulk and fibre crystal growth techniques are reviewed.