Optical Memory System Research Articles

Asymmetric 1D and 2D tunneling induced grating in Quantum Dot system

We propose a tunneling-induced grating based on the phenomenon of tunneling-induced transparency. Our method allows us to alternate between zeroth-order diffraction along with completely different higher-order diffraction patterns. This is accomplished by using four laser beams to drive quantum dots via a planar configuration. Specifically, we modulate a standing waves controlling beam which propagates orthogonal with the planar medium, while weaker planar probing beam, generated signal field, and pumping field are applied adjacent towards the medium. We quantitatively analyzed the dynamics for the phase, amplitude modulations, along with probing fields diffraction strengths of various ordering. By altering the relative phase of fields, we expect asymmetric 1D and 2D tunneling induced grating in quantum dot system. Our suggested approach has significant uses in optical memory systems, notably in the storing of information to diffraction orders via tunneling-induced grating.

Photonic Crystal Flip-Flops: Recent Developments in All Optical Memory Components.

This paper reviews recent advancements in all-optical memory components, particularly focusing on various types of all-optical flip-flops (FFs) based on photonic crystal (PC) structures proposed in recent years. PCs, with their unique optical properties and engineered structures, including photonic bandgap control, enhanced light-matter interaction, and compact size, make them especially suitable for optical FFs. The study explores three key materials, silicon, chalcogenide glass, and gallium arsenide, known for their high refractive index contrast, compact size, hybrid integration capability, and easy fabrication processes. Furthermore, these materials exhibit excellent compatibility with different technologies like CMOS and fiber optics, enhancing their versatility in various applications. The structures proposed in the research leverage mechanisms such as waveguides, ring resonators, scattering rods, coupling rods, edge rods, switches, resonant cavities, and multi-mode interference. The paper delves into crucial properties and parameters of all-optical FFs, including response time, contrast ratio, and operating wavelength. Optical FFs possess significant advantages, such as high speed, low power consumption, and potential for integration, making them a promising technology for advancing optical computing and optical memory systems.

INFORMATION REPRODUCTION SYSTEMS IN INFORMATION BUSINESS LOGISTICS

The article considers the fundamentals of the information reproduction systems formation in the optoelectronic element base for information logistics systems. The use of optoelectronic elements for information processing has been considered, namely discrete optoelectronic digital systems, analog systems, optical memory systems, optical systems of input-output of information in computers, systems based on fiber devices of neuristor type. It is emphasized that modern logistics is impossible without the active use of information technology. The functions of information support of managerial influences can be performed by information technologies used today in logistics. To perform the tasks of financial flow management, these technologies can be supplemented by modules of eye-processing of the information. Logic-clock quantron automatic devices based on optocouplers are suitable for creating parallel information operating environments, which is a universal means of converting and presenting information. This approach leads to the creation of matrix-type devices that are able not only to receive information but also to process it. One of the promising areas of use of optoelectronic matrix systems is the creation of flat operating screens for parallel reception and display of information. The paper presents the classification of operating screens according to such features as: the principle of displaying information, the type of input information, the type of output information, the method of image formation, the number of consumers of the information. The analysis of electric circuit diagram of modern LED matrix video screens, in particular of a typesetting-modular design has been presented. A comparison of the forms of organization of matrix video screens is made, and it is emphasized that the most economical in terms of the number of memory trigger elements per one LED of the display cell is a video information system based on the structure of the third group video screen. The structure of the video information system is optimized according to the criterion of optimality – the maximum image quality on the matrix screen and the minimum screen complexity, which is determined by the circuit features of the microelectronic circuits.

Preparation and characterization of photo-stimuli-responsive fibers based on lanthanide-activated phosphors and spiropyran dye

Stimuli-responsive fibers are highly desirable for their potential applications in areas such as anti-counterfeiting, optical memory systems, colorimetric sensing, and bioimaging sensors. An iridescent luminescent fibers that can achieve multi-color with long afterglow and photochromic properties is always required in color-on-demand applications. Here, a set of distinct three-primary colors luminescent fibers based on red-green-blue (RGB) system. Y2O2S:Eu3+, Mg2+, Ti4+ (red), SrAl2O4:Eu2+, Dy3+ (green), Sr2MgSi2O7: Eu2+, Dy3+ (blue) are successfully synthesized. Spiropyran and as-prepared luminescent materials are introduced into PAN fibers by a one-step extrusion wet-spinning process to achieve distinct three-primary colors luminescent photochromic fiber. These as-prepared fibers emit bright lights under excitation of ultraviolet with long afterglow. These fibers exhibit outstanding tensile properties which allow knitting or weaving them into demonstrated functional designs for aesthetic designs and encryption/decryption protocols. Comparing with previous studied stimuli-responsive fibers, our research focus on distinct three-primary colors luminescent photochromic fibers present enormous potential in 3D printing, information encryption, and next generation smart fibers.

Photochromism and Persistent Luminescence in Ni-Doped ZnGa2O4 Transparent Glass-Ceramics: Toward Optical Memory Applications

Persistent luminescence and photochromism are two fascinating optical properties that involve charge trapping via defects and their release due to an external stimulation. In both processes, it is possible to define 1 (or on) and 0 (or off) optical states. Consequently, materials with one of these phenomena find major interest in view of designing smart, anticounterfeiting, and optical information storage devices. Combining both processes within a single material can lead to a new generation of information storage phosphors, in which it may be possible to obtain three different optical states by playing on the external stimulations applied on the material. For that purpose, the elaboration of nickel-doped ZnGa2O4 spinet transparent nano-glassceramics is presented in this work. The short-wave infrared (SWIR) emission, a broad band located at ca. 1275 nm, arises from Ni2+ cations located in gallium octahedral sites. SWIR persistent luminescence, arising from the same doping ion transition, can also be monitored after UV charging. Interestingly, UV irradiation not only leads to persistent luminescence charging but also to a reversible photochromism effect. By means of a complete optical characterization study combined with electron paramagnetic resonance measurements, the origins of both the persistent luminescence emission and the photochromism are explored. Finally, a discussion on the advantages of such a material combining both persistent luminescence and photochromism properties, leading to three possible optical states of the material, is dressed in view of possible optical memory systems.

Plasmonic silver-based reversible photochromism in Ag+‒doped organomodified silicates-phosphotungstate hybrid films

We report novel Ag+‒doped ormosil-phosphotungstate (PW12O403−) hybrid films that exhibit reversible yellow photochromism based on the phosphotungstate-assisted photo-induced formation of silver nanoparticles (AgNPs) and their reversible oxidation back to Ag+ ions upon low temperature heating (60–80 °C). The sol-gel derived, dip-coated, hybrid films containing phosphotungstate anions and Ag+ ions exhibit yellow color upon UV exposure and become colorless upon simple heating. Using an array of complementary analytical techniques, we first present a detailed characterization of the prepared materials and then discuss the coloration/discoloration mechanism involved. The presence of both phosphotungstate and Ag+ ions inside the hybrid matrix is found to be imperative for achieving the photochromic behavior. Owing to the presence of AgNPs and their easily achievable coloration/discoloration, these hybrid films may find application in optical memory systems, band pass filters, non-linear optical devices, UV sensing and antibacterial coatings.

Functional doping of acrylic PMMA with photochromic dyes

Work from Poland has studied the thermodynamic and kinetic stability of PMMA when doped with a photochromic dye molecule. Visible light absorption is induced in fabricated photochromic PMMA fibres for optoelectronic device applications. PMMA fibres doped in local regions with Bis-MSB under UV irradiation. Molecular switches are molecules that display a binary response when exposed to specific conditions or stimuli. A common example of this is a structural change in molecular switch materials when exposed to UV radiation. This means that meta-stable, higher-energy structural orientations of a molecule can appear under UV irradiation. A switching phenomenon between low- and high-energy geometries is often fully reversible making these systems suitable for use in several applications including optical switches, attenuators, holograms, optical memory, and smart textiles. The chemical structure of Photochromic Bis-MSB incorporated into PMMA fibres. PMMA, poly(methyl methacrylate), is a transparent thermoplastic material that is versatile, strong and recyclable. PMMA optical fibres offer numerous benefits, including high flexibility and numerical aperture, low production cost, and good biocompatibility. A current limitation of PMMA fibres compared to optically active silica fibres is relatively high optical absorption in the visible and near infrared region of the electromagnetic spectrum. The incorporation of photosensitive dyes introduces additional absorption bands and increases the frequencies of light that are absorbed by the material. A common photochromic dye, 1,4-bis(2-methylstyryl)benzene (Bis-MSB), displays high transmittance in the visible region of the electromagnetic spectrum. Bis-MSB also behaves as a molecular switch when exposed to light, where its geometry is changed from linear (cis) to bent (trans) configurations following bond rotation. Thus, incorporating Bis-MSB into PMMA creates a coloured material with controllable and reversible broad-range light absorption. Coloured photoresponsive materials that are transparent, such as Bis-MSB doped PMMA, are favourable polymer materials for organic electronics as they efficiently absorb light within a useful region of the electromagnetic spectrum. In this issue of Electronics Letters, Dr Piotr Miluski and colleagues at Bialystok University of Technology, Poland, fabricate Bis-MSB-doped PMMA and report the optical transmission properties and kinetic relaxation lifetimes of this unique material. Following fabrication of the Bis-MSB PMMA fibres, the samples were exposed to high-energy UV radiation with a 1 MW peak power at 355 nm laser. A colour change was immediately observed, which visibly demonstrates the molecular structural switch of Bis-MSB under UV radiation. A comparison of light transmission between the undoped fibres and the Bis-MSB-doped PMMA fibres is made in the paper. This comparison shows the frequency change of light absorption due to the presence of the dopant molecules and demonstrates that the dopant induces wideband visible light absorption between 400–670 nm. This range of wavelengths is of particular interest for solar cell applications. Thermal relaxation was shown to lead to the decolouration of the fabricated polymer fibres, which was further supported by measured relaxation times in an analysis of the kinetic properties of the system. Long relaxation times can be useful for UV indicators and optical memory systems. The “Main advantage of (Bis-MSB) doped PMMA is that it offers high transmittance of its lower energy form in the VIS spectrum range” said Miluski. The ability to harness and modulate the optical properties of a molecule and control its free-volume as it rotates from linear to bent is well demonstrated within this paper. The development of organic-based functional materials for optical fibre technology introduces some limitations, including organic breakdown at high temperatures, solvent evaporation and low thermal conductivity of polymers. Moreover, the dopant distribution and polymer host homogeneity have to be carefully controlled to ensure a continuous optical response throughout the material. Recent research developments in the field of smart organic materials offer new functional properties that do not suffer from the described disadvantages. Low-energy consumption of organic devices offers significant advantages over well-developed silicon-based electronics. In the field of photochromic polymers, one of the main challenges is the ability to modulate high-frequency optical properties. Dr Miluski predicts that photochromic PMMA fibres will be appropriate for use in real-time holograms and for optical radiation modulation in telecommunication applications. Ultra-stable cis/trans isomerisation is also strongly desired in the field of logical gates and optical memory, where the use of photo-responsive PMMA fibres could offer both lower power consumption and higher storage density.

Optical memory system based on incoherent recorder and coherent reader of multiplexed computer generated one-dimensional Fourier transform holograms

The present article highlights the development results of archive memory holographic system based on application of computer generated Fourier holograms. The proposed idea allows realization of holographic principles of digital data record using simple and compact optical devices. Special interest is paid to synthesis and multiplexed record of one-dimensional Fourier transform holograms. The principal schemes of constructed prototypes of incoherent data recorder and coherent data reader are described in the present paper. The results of experimental implementation of the constructed devices are presented.

Development of projection-type optical scheme for computer-generated Fourier hologram recorder

Projection-type recorders of computer-generated Fourier holograms have potential due to the decreased precision requirements of the optical scheme compared to most known holographic data recorders based on two-beam schemes. In the case of optical memory system development, the reduction factor of the projection scheme requires the application of properly developed optical components. The present report is dedicated to the development of special objectives for the projection scheme of computer-generated Fourier holograms.

Second-Order Nonlinear Optical Properties of a Dithienylethene-Indolinooxazolidine Hybrid: A Joint Experimental and Theoretical Investigation.

The nonlinear optical (NLO) properties of a double photochrome molecular switch are reported for the first time by considering the four trans forms of a dithienylethene-indolinooxazolidine hybrid. The four forms are characterized by means of hyper-Rayleigh scattering (HRS) experiments and quantum chemical calculations. Experimental measurements provide evidence that the pH- and light-triggered transformations between the different forms of the hybrid are accompanied by large variations of the first hyperpolarizability, which makes this compound an effective multistate NLO switch. Quantum chemical calculations conducted at the time-dependent Hartree-Fock and time-dependent DFT levels agree with the experimental data and allow a complete rationalization of the NLO responses of the different forms. The HRS signal of the forms with an open indolinooxazolidine moiety are more than one order of magnitude larger than that measured for the other forms, whereas the open/closed status of the dithienylethene subunit barely influences the dynamic NLO properties. However, extrapolation of the NLO responses to the static limit leads to univocally distinguishable intrinsic responses for three of the various forms. This hybrid system thus acts as a highly efficient multistate NLO switch for eventual exploitation in optical memory systems with multiple storage and nondestructive readout capacity.

Specificities of data page representation in projection type optical holographic memory system

The matter of the present article covers the results obtained during the development of holographic memory record system based on projection of computer-generated amplitude Fourier holograms. The basic issue is the investigation of representation specificities of binary data pages, which were choose to be encoded on computer-generated amplitude Fourier hologram and then recorded on photosensitive medium as microhologram using simple projection optics and spatial light modulator. Limitations of data page resolution caused by limited resolution of SLM that is used to display the digitally synthesized holograms are discussed. Also the results of random phase coding of data page during the holograms synthesis research are presented.

Influence of laser parameters on information capacity of communication channel

Contemporary tendencies in developing computing and communication systems are, more than ever, pointing out the necessity of transfer from computer and information systems to the optic and even quantum ones [1---4]. Saturation of microelectronics potencies can be seen in the simple and obvious facts, i.e. slowdown of effectiveness increase rates for the classical Turing computing systems and transfer to multicore parallel computations in electronics, as well as greater attention is paid to the optical communication channels, memory and data transmission systems, which is due to high density of information pack in the optical spectrum of electromagnetic waves [5---7].Taking into account the classical Shannon's understanding of the information quantity and specific characteristics of an optical communication channel, in this work, we are trying to draw a parallel between the classical communication channel and the quantum one, which enables us, in some simple cases, to consider the approximate dependence of maximum information transmission rate on the key characteristics of laser emitter, including the average transmission power, bandwidth, and polarization.

Helicity Control of π‐Stacked Assemblies of Oligo(para‐phenylene) Derivatives Using Photoresponsive Chiral Moieties at Terminal Sites

Oligo(para‐phenylene) (OPP) derivatives bearing photoresponsive chiral dithienylethene (DE*) terminal moieties that induce chirality in the OPP main chain are synthesized. In the assembled state, the photoisomerization of the chiral DE* terminal moieties prior to assembly, from the open to the closed form, leads to a change in the helicity of the π‐stacked structures. The circular dichroism spectra of mixed solvent solutions and cast films of the OPP assemblies exhibit bisignate Cotton effects in the absorption region associated with the oligomer main chain: these features indicate the presence of helically π‐stacked structures. Furthermore, the chiral transcription of racemic poly(bithiophenethiophene) (PBTT) by chiral OPP in the assembled state is demonstrated. The chirally transcribed PBTT shows a change in helicity upon the photoisomerization of the chiral DE* terminal moieties of OPP. To the best of our knowledge, this is the first report of helicity control of a helically π‐stacked conjugated oligomer through the photoisomerization of a chiral photoresponsive moiety. Such assemblies could be attractive for use in optoelectronic devices and optical memory systems.

Generation of fuzzy rules and learning algorithm for servo control in holographic data storage system

Today many media of information storage device are formed as disks. Hence, next generation removable data storage media are shaped as disk types too. The holographic data storage system also uses a disk type photopolymer media. And then, holographic data storage system is most advanced optical memory system. Tracking servo and tilt servo control are very important research in holographic data storage system. In this paper, we propose intelligent servo control by fuzzy rules in holographic data storage system. Hence, we have found pattern of tilt servo control in holographic data storage system through fuzzy system and genetic algorithm. Fuzzy rules were generated by genetic algorithm for controlling tilt servo. Therefore, we control tilt servo using fuzzy rules in holographic data storage system. Consequently, Image input---output patterns of tilt servo control was found by intelligence algorithm in holographic data storage system.

On the design of a 3D optical interconnected memory system

On the design of a 3D optical interconnected memory system

ChemInform Abstract: Fluorescent Photochromes of Diarylethene Series: Synthesis and Properties

AbstractReview: 216 refs.

Near-field recording on phase-change nanoparticles and reflective reproduction from nanoantenna utilizing plasmonic resonance for high-density optical memory

For high-density optical memory system, near-field recording on a medium with phase-change nanoparticles and dual metal layers was proposed. A finite difference time domain (FDTD) analysis demonstrated that a combination of a nanoantenna with such a medium so as to enhance plasmonic resonance would enable effective recording with larger (~10 times) working distance (WD) than for a conventional medium. A reproduction method of detecting the intensity of the reflected wave from the nanoantenna was also proposed in the same setup as the recording. We found that plasmonic resonance induced in the nanoantenna was enhanced and the intensity of reflected light was also increased when the phase state of nanoparticle was crystalline. Since the sub-diffraction limited size of nanoantenna is larger than a nanoparticle, the detected signal intensity can be greatly improved. Calculated results showed that our proposed system and methods for recording and reproduction would have a potential to become effective solutions for terabyte-class optical memory system.

Pattern analysis for tilt servo control in holographic data storage system

Today many media of information storage device are formed as disks. Hence, next generation removable data storage media are shaped as disk types too. The holographic data storage system also uses a disk type photopolymer media. And then, holographic data storage system is most advanced optical memory system. In 1948, Dennis Gabor made the insightful observation that the phase formation in a diffracted wavefront could be recorded by interference with a coherent background. It was not until the early 1960s with the invention of the laser that the technology became practical for storing and retrieving images, and the concepts of holographic data storage were established by van Heerden. In his seminal paper in 1963 on the theory of optical information storage in solids, van Heerden postulated that the recording of interference patterns in a three-dimensional medium could be used as a means of storing and retrieving information (Holographic data storage, Springer, New York, 2000). Tracking servo and tilt servo control are very important research in holographic data storage system. In this paper, we propose intelligent servo control by fuzzy rules in holographic data storage system. Hence, we have found pattern of tilt servo control in holographic data storage system through fuzzy system. Fuzzy rules were generated by subtractive clustering algorithm for controlling tilt servo. Therefore, we control tilt servo using fuzzy rules in holographic data storage system. Consequently, practical pattern of tilt servo control was found by intelligence algorithm in holographic data storage system (Holographic data storage, Springer, New York, 2000).

How I knew him

Academician Andrey L. Mikaelian, the outstanding scientist with world name in the field of SHF technique, quantum electronics, holography, optical memory systems and neural networks passed away on 7 July 2010.

A simultaneous generation of QKD and QDC via optical memory array for distributed network security

We propose a novel system of a simultaneous generation of continuous variable quantum key distribution (QKD) and quantum dense coding (QDC) via an optical memory array. The optical memory system is formed by using an array waveguide incorporating a nano-ring resonator, whereas the different spatial light modes can be generated and stored within an optical memory unit. The polarized photon is formed and stored within a storing device, i.e. a ring resonator, whereas the different time slot entangled photons can be generated, transmitted and detected by the different subscriber in the distributed networks. By using the optical memory concept, the continuous variable quantum key distribution is provided. Furthermore, the use of quantum dense coding via time division multiplexing paths, i.e. different time slot, is also plausible. The advantage of the proposed system is that the quantum key distribution can provide the network top security with high capacity and safety, which is the large demand of usage in the public networks.