Three-dimensional Optical Data Storage Research Articles

Threshold response using modulated continuous wave illumination for multilayer 3D optical data storage

In order to achieve a high capacity 3D optical data storage medium, a nonlinear or threshold writing process is necessary to localize data in the axial dimension. To this end, commercial multilayer discs use thermal ablation of metal films or phase change materials to realize such a threshold process. This paper addresses a threshold writing mechanism relevant to recently reported fluorescence-based data storage in dye-doped co-extruded multilayer films. To gain understanding of the essential physics, single layer spun coat films were used so that the data is easily accessible by analytical techniques. Data were written by attenuating the fluorescence using nanosecond-range exposure times from a 488 nm continuous wave laser overlapping with the single photon absorption spectrum. The threshold writing process was studied over a range of exposure times and intensities, and with different fluorescent dyes. It was found that all of the dyes have a common temperature threshold where fluorescence begins to attenuate, and the physical nature of the thermal process was investigated.

CW Optical Limiting Study in Disperse Yellow Dye-doped PMMA-MA Polymer Films

<div><p><em>Molecules with high two-photon absorption (TPA) cross section and the molecules which have reverse saturation absorption (RSA) cross section are of great interest today because of their application in three-dimensional optical data storage and photonic switches. During last forty years, several techniques have been developed to determine the two-photon absorption cross-sections and reverse saturation absorption cross-sections of the materials. This includes direct methods, such as nonlinear transmission and Z-scan methods and indirect methods, such as two-photon excited fluorescence and two-photon pump-probe transient absorption spectroscopy. During recent years, the organic dye-doped polymer films getting more attention due to their advantages to fabricate photonics devices. In this paper, we have studied the nonlinear optical properties like nonlinear absorption and nonlinear refraction of an azo dye Disperse yellow-7 (DY-7) doped in Polymethyl methacrylate-methacrylic acid (PMMA-MA) polymer matrix using open aperture and closed aperture Z-scan experimental methods using continuous wave (CW) laser. The optical limiting properties of these films are also studied in Type 1 and Type 2 configurations at different input power using continuous wave (CW) laser beams of 532 nm wavelength.</em></p></div>

Cavity-enhanced eigenmode and angular hybrid multiplexing in holographic data storage systems.

Resonant optical cavities have been demonstrated to improve energy efficiencies in Holographic Data Storage Systems (HDSS). The orthogonal reference beams supported as cavity eigenmodes can provide another multiplexing degree of freedom to push storage densities toward the limit of 3D optical data storage. While keeping the increased energy efficiency of a cavity enhanced reference arm, image bearing holograms are multiplexed by orthogonal phase code multiplexing via Hermite-Gaussian eigenmodes in a Fe:LiNbO3 medium with a 532 nm laser at two Bragg angles. We experimentally confirmed write rates are enhanced by an average factor of 1.1, and page crosstalk is about 2.5%. This hybrid multiplexing opens up a pathway to increase storage density while minimizing modification of current angular multiplexing HDSS.

Multifocal array with controllable orbital angular momentum modes by tight focusing

Multifocal spots arrays with controllable three-dimensional (3D) position, orbital angular momentum (OAM) and the number of focal planes along longitudinal direction have been proposed and investigated by using a special designed phase-only multi-zone plate at the back aperture of a high numerical aperture (NA) objective. By using Debye diffraction integral, the focusing field could be rewritten as a fast Fourier transform (FFT), which is the theory and principle for generating the controllable OAM-modes focusing spots. According to this theory, a hybrid multi-zone plate at the back aperture of a high NA objective is designed for the illuminations of the radially polarized Bessel–Gaussian beam. Each focusing spot in the focal plane is generated by independent parts, so the multiplexing OAM-modes could be realized by focusing two or more spots at the same position with different orthogonal eigenstates. It is a practical and flexible OAM multi-focus technique with dynamically controllable 3D position, number of focal planes, corresponding topological charges and focal lengths to meet different requirements, such as 3D optical data storage, air-core fiber coupler and parallel optical manipulation.

Multiphoton harvesting metal-organic frameworks.

Multiphoton upconversion is a process where two or more photons are absorbed simultaneously to excite an electron to an excited state and, subsequently, the relaxation of electron gives rise to the emission of a photon with frequency greater than those of the absorbed photons. Materials possessing such property attracted attention due to applications in biological imaging, photodynamic therapy, three-dimensional optical data storage, frequency-upconverted lasing and optical power limiting. Here we report four-photon upconversion in metal–organic frameworks containing the ligand, trans, trans-9,10-bis(4-pyridylethenyl)anthracene. The ligand has a symmetrical acceptor–π–donor–π–acceptor structure and a singlet biradical electronic ground state, which boosted its multiphoton absorption cross-sections. We demonstrate that the upconversion efficiency can be enhanced by Förster resonance energy transfer within host–guest metal–organic frameworks consisting of encapsulated high quantum yielding guest molecules. Using these strategies, metal–organic framework materials, which can exhibit frequency-upconverted photoluminescence excited by simultaneous multiphoton absorption, can be rationally designed and synthesized.

Very Fast Algorithms for Eliminating the Diffraction Effects in Protein-Based Volumetric Memories

One of the current research directions in biological nanotechnology is the useof bacteriorhodopsin in the fabrication of protein-based volumetric memories.Bacteriorhodopsin, with its unique light-activated photocycle, nanoscale size,cyclicity (>107), and natural resistance to harsh environmental conditions,provides for protein-based volumetric memories that have a comparativeadvantage over magnetic and optical data storage devices. The constructionof protein-based volumetric memories has been, however, severely limited byfundamental issues that exist with such devices, such as unwanted diffractioneffects. In this paper, we propose some optimizations that can be applied to oneof the previously proposed algorithms for eliminating the diffraction effects.

Novel carbazole derivatives with quinoline ring: Synthesis, electronic transition, and two-photon absorption three-dimensional optical data storage

We designed carbazole unit with an extended π conjugation by employing Vilsmeier formylation reaction and Knoevenagel condensation to facilitate the functional groups of quinoline from 3- or 3,6-position of carbazole. Two compounds doped with poly(methyl methacrylate) (PMMA) films were prepared. To explore the electronic transition properties of these compounds, one-photon absorption properties were experimentally measured and theoretically calculated by using the time-dependent density functional theory. We surveyed these films by using an 800nm Ti:sapphire 120-fs laser with two-photon absorption (TPA) fluorescence emission properties and TPA coefficients to obtain the TPA cross sections. A three-dimensional optical data storage experiment was conducted by using a TPA photoreaction with an 800nm-fs laser on the film to obtain a seven-layer optical data storage. The experiment proves that these carbazole derivatives are well suited for two-photon 3D optical storage, thus laying the foundation for the research of multilayer high-density and ultra-high-density optical information storage materials.

Space-selective precipitation of ZnO crystals in glass by using high repetition rate femtosecond laser irradiation.

We report on three-dimensional (3D) precipitation of ZnO crystals inside a silicate glass by a 500 kHz femtosecond pulse laser. The precipitation and distribution of ZnO crystals in glass are confirmed and analyzed by Raman spectra and Raman mapping. Mirco- luminescence is observed in the laser modified region when excited by femtosecond pulse laser or Xenon lamp. The effect of laser average power on the precipitation of the ZnO crystals has also been investigated. The possibility of 3D optical data storage using the observed phenomena is demonstrated.

Coping with Diffraction Effects in Protein-Based Volumetric Memories: Current Challenges and Possible Solutions

Coping with Diffraction Effects in Protein-Based Volumetric Memories: Current Challenges and Possible Solutions

Nonlinear fluorescence modulation of an organic dye for optical data storage

Most approaches to high-capacity 3D optical data storage (ODS) require confinement of the writing action to a specified depth in the writing medium. This is achieved by a nonlinear photoresponse, usually two-photon absorption, which requires a pulsed long-wavelength source. Fluorescence photobleaching of a dye/polymer composite can be used at a short wavelength to store data at the diffraction limit in a layered storage medium. In this work, the writing response of a bleachable dye/polymer system illuminated with single pulses of various duration obtained from a modulated 405 nm wavelength CW laser was studied. A transition from a linear to nonlinear writing mechanism was observed near the microsecond time scale. Concentration-dependent measurements indicate that a photothermal mechanism accounts for the nonlinear response in the short pulse, higher power regime. This nonlinear response may be useful for realizing terabyte scale ODS in multilayered polymer media.

Storage and Processing of Information Using Molecules: The All‐Photonic Approach with Simple and Multi‐Photochromic Switches

AbstractThe use of photochromes for the implementation of molecular logic operations is a very promising approach toward molecular computing. This statement is based on a) the possibility of operating such molecular devices exclusively with photonic signals and b) spatiotemporally and remotely controlled switching, which is characteristic for photochromes. Herein, a brief overview of the application of simple photochromes and multi‐photochromic conjugates for the small‐scale functional integration of complicated logic circuits is given. This complements and extends efforts to design molecular photochromic memories for data storage described by many research groups worldwide.

Fast Algorithms for Coping with Diffraction Effects in Protein-Based Volumetric Memories (Design and Implementation)

Fast Algorithms for Coping with Diffraction Effects in Protein-Based Volumetric Memories (Design and Implementation)

Modeling the diffraction efficiency of holographic microgratings

Microlocalized holographic reflection gratings enable high-density three-dimensional optical data storage. Diffraction of light by these microholograms is modeled using a far-field approximation of the volume integral, which reduces the computational effort from 3D to 1D numerical integration. With this method, the diffraction efficiency is calculated, spatially resolved in terms of the dependence on the lateral and longitudinal scan position. The impact of the numerical aperture is analyzed. The potential of wavelength multiplexing is investigated by calculating the wavelength selectivity of microholograms.

Two-Photon Three-Dimensional Optical Storage of a New Photobleaching Material

Two-photon three-dimensional optical data storage is an important method to realize high density storage and ultra-high density storage. This paper introduces the the basic principle of two-photon photobleaching optical storage, describes two-photon three-dimensional optical storage system and the absorption and fluorescence spectra of a new type of photobleaching materials BASF in detail, carries out the experimental study that two-photon information is written and read out against a new photobleaching material of BASF using femtosecond pulse laser wavelength is 800nm, and realize two layers of optical information storage, the information point spacing is 8μm and the interlayer distance is 15μm; two-layer information point signal strength is recognized using Recognition algorithm. The experiment proved that new photobleaching material of BASF can be used for two-photon three-dimensional optical storage, that has laid a solid foundation for the high-density and ultra-high density optical information storage materials research.

Three-dimensional Dammann array

We demonstrate a scheme that can produce a three-dimensional (3D) focus spot array in a 3D lattice structure, called a 3D Dammann array, in focal region of an objective. This 3D Dammann array is generated by using two separate micro-optical elements, a Dammann zone plate (DZP) that produces a series of coaxial focus spots and a conventional two-dimensional (2D) Dammann grating (DG). A simple, fast, and clear method is presented to design this binary pure-phase (0,π) DZP in vectorial Debye theory regime. Based on this kind of DZP, one can always obtain a 3D Dammann array both for low and high numerical aperture (NA) focusing objectives. For experimental demonstration, an arrangement combining a DZP, a 2D DG, and a pair of opposing lenses is proposed to generate a 5×5×5 Dammann array in focal region of an objective with NA=0.127 and another 6×6×7 Dammann array for an objective of NA=0.66. It is shown that this arrangement makes it possible to achieve 3D Dammann arrays with micrometer-sized focus spots and focus spacings of tens of micrometers for various practical applications, such as 3D parallel micro- and nanomachining, 3D simultaneous optical manipulation, 3D optical data storage, and multifocal fluorescence microscope, etc.

Enhanced Two-Photon 3D Optical Storage in a Novel Multibranched-Dye Doped Photobleaching Polymer

A novel multibranched nonlinear dye，4, 4´, 4´´-tris(9-carbazyl-trans-styryl) triphenylamine (TCSTPA)，has been designed and synthesized aimed at two-photon absorption applications. Two-photon absorption cross section of the multibranched dye was obtained as high as 2.35×10-47cm4s photon-1molecule-1pumped with femtosecond laser beam at 800 nm. One-photon and two-photon absorption optical properties were demonstrated in solutions. Three-dimensional (3D) optical data storage experiments were carried out by two-photon photobleaching in the multibranched-dye doped polymethylmethacryate (PMMA) with a 3D data storage density of approximate 14 Gbits/cm3. Research on the two-photon photobleaching ability shows the novel two-photon absorption dye with multibranched molecular motif has higher photosensitivity than traditional linear two-photon absorption dyes do.

The Hardware and Software Design of Dual Pick-up Head Three-Dimensional Optical Storage System

Femtosecond laser two-photon three-dimensional optical data storage is an effective method for high capacity data storage. In this paper, system construction is analyzed in detail from hardware and software aspects for dual pick-up head three-dimensional optical storage systems. Three-dimensional optical storage system is conposed of the fluorescence reader module and the servo control module, firstly analyzes the read and write process of three-dimensional optical storage by 89c52 MCU controling from the hardware. Then, the software is analyzed in detail, the software consists of two parts: the lower computer software and PC software. lower computer software achieves communication and control related to hardware, PC software is used to facilitate the control of the experimental system. Two CPU control software is introduced, and controlling process of PC software control is analyzed in detail. These work has laid a solid foundation for the practical of three-dimensional optical storage technology.

Efficient Algorithms for Computing With Protein-Based Volumetric Memory Processors

With an ever increasing volume of digital data there is a huge increase in the demand for much faster, smaller, and denser storage technologies. Conventional 2-D (surface) storage/memory technologies may soon be replaced with much faster and denser 3-D volumetric (holographic) storage technologies. Photo sensitive protein bacteriorhodopsin has been proven to have great chemical, thermal, and holographic properties and is a good choice for both associative and volumetric memories. Associative memory systems have a wide range of practical applications. However, there is a lack of a formal computational model that can be used to analyze the performance of different algorithms on architectures that support associative memory. We first address this issue by defining a new computational model on protein-based associative memory processors. We also present and analyze algorithms for several fundamental problems on this new model. Secondly, we employ balanced modulated codes in volumetric memories to reduce the bit error rate and improve fidelity. Conventional coding schemes such as 6:8 coding, limit the size of the page to 8 bits and achieve a code rate (utility) of only 75%. As the technology matures we need efficient algorithms to produce these codes with better utility. In this paper, we address this problem and give algorithms that can generate these codes with superior utility.

Research on the Application of DVD Pick-Up Head in Three-Dimensional Optical Storage

Two-photon three-dimensional optical data storage is an effective method for high capacity data storage. Based on DVD pick-up head and two-photon absorption, two-photon three-dimensional optical disk storage system is built, and operating principle of the overall system is in detail. In the servo module of three-dimensional optical disk storage system, DVD circuit control board (MT1389SE) is conducted on three-point improvement: extract focus servo error signal and servo error signal, increase four communications interfaces，increase photoelectric detectors; the extraction of focus and track servo signal on reading and writing module is analyzed in detailed. The measured principles and methods of the voice coil motor characteristic curve of Sanyo DVD pick-up head (SF-HD60S) are analyzed in detailed by using dual-frequency laser interferometer, which can be well meet the layer selection requirements of three-dimensional optical storage. DVD pick-up head applied in three-dimensional optical storage overcomes the limitations of three-dimensional scanning stage, integrates with existing DVD servo technology, and lays a solid foundation for practical use of two-photon three-dimensional optical storage.

Superresolution-focal-volume induced 30 Tbytes/disk capacity by focusing a radially polarized beam

This paper reports on the study of the superresolution volume of the focal spot by focusing a radially polarized beam. This feature is achieved by increasing the inner radius of a high NA annular objective to break the diffraction-limited volume of a focal spot. The application of this finding into two-photon induced three-dimensional optical data storage leads to an enhanced photoreduction threshold effect in recording. As such, multilayer subdiffraction optical recording is experimentally demonstrated with an equivalent capacity of 3.0 Tbytes/disk.