Optical Information Storage Research Articles

Generation of separation-locked bound solitons in a passively mode-locked all-fiber laser with a Fabry-Perot microcavity

We report the generation of separation-locked bound solitons in a passively mode-locked all-fiber laser with a Fabry-Perot (F-P) microcavity. The laser cavity can deliver several kinds of bound solitons with the fixed soliton separation of 4.7 ps, corresponding to the F-P cavity length of 700 μm. The single-shot spectra capturing technique reveals that the observed bound soliton is directly generated from continuous wave without experiencing single-soliton mode-locking process. The numerical results are in good agreement with the experimental observations and further confirm that the generation of bound solitons with locked separation is attributed to the F-P microcavity. The demonstration provides a versatile method to generate several types of separation-locked bound solitons by using F-P microcavity with diverse cavity lengths and reflectivities, which play vital roles in fiber sensor and optical information storage.

Recent Progress in Light-Driven Molecular Shuttles.

Molecular shuttles are typical molecular machines that could be applied in various fields. The motion modes of wheel components in rotaxanes could be strategically modulated by external stimuli, such as pH, ions, solvent, light, and so on. Light is particularly attractive because it is harmless and can be operated in a remote mode and usually no byproducts are formed. Over the past decade, many examples of light-driven molecular shuttles are emerging. Accordingly, this review summarizes the recent research progress of light-driven molecular shuttles. First, the light-driven mechanisms of molecular motions with different functional groups are discussed in detail, which show how to drive photoresponsive or non-photoresponsive molecular shuttles. Subsequently, the practical applications of molecular shuttles in different fields, such as optical information storage, catalysis for organic reactions, drug delivery, and so on, are demonstrated. Finally, the future development of light-driven molecular shuttle is briefly prospected.

Multi-mode readout via opto-mechano-photothermo-responsive luminescence from electron trapping material for optical information storage application

Optical storage material is one of the promising candidates for next generation of information memory medium owing to large capacity, reusable rewritable, and rapid response performance. However, as the typical optical storage medium, electron trapping materials (ETMs) are limited in applications of information preservation or optical display technology due to their single readout route relying on photostimulated luminescence (PSL). A crucial limitation to the feasibility of multi-mode optical information readout is the inevitable mismatch between trap depth and the energy of external stimuli. In this study, by introducing Bi3+ ions as intermediate levels between deep traps and emitters, we developed a LiTaO3:Tb3+/Bi3+ (LTO) material that can simultaneously response to optical, mechanical, and thermal stimuli efficiently, showing as multiple trap-controlling luminescence. The tantalate material was endowed with opto-mechano-responsive readout capacity when assembled with polymer matrix. Moreover, by utilizing LiCaYb0.5Nd0.5(WO4)3 microcrystals (LCYW) with near-infrared-induced photothermy property, we designed a LTO-LCYW bilayer composite film then achieved non-contact thermo-responsive readout of optical information via photothermo-stimulated luminescence. These findings provide a unique perspective for designing multi-mode responsive luminophors and photonic devices towards widespread applications, especially optical display, optical memory technology, and anticounterfeiting.

Large reversible upconversion luminescence modification and 3D optical information storage in femtosecond laser irradiation-subjected photochromic glass

Fast response, high luminescence contrast, three-dimensional (3D) storage, and nondestructive reading are key factors for the optical storage application of photochromic materials. Femtosecond (fs) laser direct writing technology with multiphoton nonlinear absorption is becoming a useful tool for microprocessing functional units in the 3D space of glass owing to its remarkable advantages, such as a fast processing speed and high processing accuracy. Herein, the photochromism of transparent glass codoped with rare-earth ions was investigated under 800-nm fs laser irradiation, affording a fast response. The photochromic glass achieves an upconversion luminescence (UCL) modification of 92%. The photochromic glass can be bleached back to its original color using heat treatment. The transmittance and UCL modification show excellent reproducibility under alternating stimulations between 800-nm fs laser irradiation and heat treatment. The data can be written in the interior of the transparent photochromic glass using 800-nm fs laser irradiation, facilitating 3D information storage. These results suggest that the 800-nm fs laser irradiation-subjected photochromic glass is an ideal optical data storage medium.

Light–Heat and Light–Light Dual-Controlled Upconversion Luminescence and Photochromic Processes in Er-Activated Bi7Ti4NbO21 for Optical Information Storage

Light–Heat and Light–Light Dual-Controlled Upconversion Luminescence and Photochromic Processes in Er-Activated Bi₇Ti₄NbO₂₁ for Optical Information Storage

SrAl2O4 crystallite embedded inorganic medium with super-long persistent luminescence, thermoluminescence, and photostimulable luminescence for smart optical information storage

As a leader of long persistent luminescence (LPL) materials, the optical properties of aluminate phosphor have remained unsurpassed for many years. As a powder material, its practical application will always be limited to the field of security signs. In this paper, the SrAl 2 O 4 : Eu 2 + , Dy 3 + inorganic solid material with comparable LPL properties to powder materials was obtained. The crystallization mechanism and crystallite micro-morphology of inorganic glass materials have been studied, and a new opinion is put forward that the large-size SrAl 2 O 4 crystallites in the glass matrix are stacked by rod-shaped crystals arranged in a regular direction. In addition, the SrAl 2 O 4 : Eu 2 + , Dy 3 + glass obtained cannot only collect high-energy photons but also is sensitive to low-energy sunlight. The results show that the material exhibits superior performance in LPL, thermoluminescence, and photostimulable luminescence. Based on this property, a new application of this material in the field of information storage was explored. This paper has a certain reference value for the development and application of aluminate LPL materials in the field of smart optical information storage.

Designing photochromic materials with high photochromic contrast and large luminescence modulation for hand-rewritable information displays and dual-mode optical storage

Inorganic photochromic materials have been identified as attractive possibilities in many photonic applications due to their outstanding thermal stability and eminent fatigue resistance. However, the relatively low photochromic contrast of inorganic photochromic materials restricts their further development. A novel method for achieving high photochromic performance is presented in this paper through volatilization element selection, high temperature sintered and low-valence ion doping. The obtained Ba(Zr0.16Mg0.28Ta0.56)O3 ceramics exhibits an ultra-high photochromic contrast of 62.1% with a fast response time of 3 s upon alternate 365 nm illumination and 350 °C thermal stimulus (or 450 nm illumination), which presents the best performance among the inorganic photochromic materials. Benefiting from these excellent properties, Ba(Zr0.16Mg0.28Ta0.56)O3 is the pioneer inorganic photochromic ceramics to support real-time handwriting and photobleaching information display. Moreover, due to the perfect overlap between the absorption band of Ba(Zr0.16Mg0.28Ta0.56)O3:0.05%Pr3+ after 365 nm illumination and the excitation/emission peak of Pr3+, a large luminescence modulation of 92.5% is achieved, which reveals the great potential of Ba(Zr0.16Mg0.28Ta0.56)O3:0.05%Pr3+ in dual-mode optical information storage. This work is expected to provide a significant guidance for the design of high performance inorganic photochromic materials and promote the applications in optical information storage.

Bi-Induced Photochromism and Photo-Stimulated Luminescence with Fast Photochromic Response for Multi-Mode Dynamic Anti-Counterfeiting and Optical Information Storage

Bi-Induced Photochromism and Photo-Stimulated Luminescence with Fast Photochromic Response for Multi-Mode Dynamic Anti-Counterfeiting and Optical Information Storage

Excitation Wavelength-Dependent Multi-Emission in Sb3+/Bi3+/Er3+ Codoped Perovskite Toward Optical Anti-Counterfeiting and Information Storage

Excitation Wavelength-Dependent Multi-Emission in Sb3+/Bi3+/Er3+ Codoped Perovskite Toward Optical Anti-Counterfeiting and Information Storage

Visible-Light-Controlled Ternary Chiroptical Switches with High-Performance Circularly Polarized Luminescence for Advanced Optical Information Storage and Anti-Counterfeiting Materials

Visible-Light-Controlled Ternary Chiroptical Switches with High-Performance Circularly Polarized Luminescence for Advanced Optical Information Storage and Anti-Counterfeiting Materials

Temperature-dependent long persistent luminescence properties and trap distributions in Sr2MgAl22O36: Eu2+

Long persistent luminescence (LPL) materials can be released its stored energy by various temperature induced thermal disturbance for a period of time. However, the accelerated release of trapped carriers at higher temperatures inhibits the use of LPL materials in extreme environments. In this work, a series of blue-emitting LPL phosphors Sr2MgAl22O36: Eu2+ were prepared by high temperature solid phase reaction. The investigation of photoluminescence (PL) and LPL preliminary indicated that the optimal room-temperature LPL time is 80 s, and the depth of trap was about 0.84 eV and 1.078 eV. Analyses of temperature-dependent LPL decay curves and thermoluminescence (TL) spectra show that the LPL initial brightness and duration time increase first and then decrease with the increase of temperature, and the optimal temperature is 453 K. These findings ensure the application of the discovered LPL phosphors above room temperature, including optical information storage and anti-counterfeiting among others.

The role of boric acid in optical information storage properties in Eu doped BaSi2O5

Optical information storage technology is emerging, therefore materials suitable for optical write-in and read-out are in demand. In this study the influence of boric acid addition during synthesis on the optical information storage properties of BaSi2O5:Eu material, that has been recently offered as a perspective material for this application. A thorough investigation is carried out to establish the relationship between boric acid addition, phase composition and photostimulated luminescence performance of the samples. The present work demonstrates the influence of the boric acid addition on the trapping center distribution in the material, thus leading to the improvement of photostimulated luminescence intensity. This can lead to the optimization of BaSi2O5:Eu material for optical information storage.

Halogen-perovskite metasurfaces for trichromatic channel color holographic imaging

Halogen perovskites have high refractive indexes and adjustable bandgaps, making them promising materials for all-dielectric and tunable metasurfaces. Herein, we design tunable polarization-converted halogen-perovskite metasurfaces and explained their characteristics in theory by using the Jones matrix. We propose a halogen-perovskite color holographic metasurface with low crosstalk owing to the excellent monochromatic permeability of three halogen perovskites (MAPbCl3: 450 nm; MAPbBr3: 550 nm; MAPbI3: 740 nm). In addition, we build three independent imaging channels to prevent color crosstalk between them to achieve fantastic imaging applications. This study serves as a good reference for research on optical information storage, polarization optics, holographic image encryption.

Ultrafast Photochromic Self‐Healing Polymer Gels with Tunable Fluorescence

AbstractPhotoresponsive self‐healing polymer gels have great potential in the fields of optical information storage, artificial intelligence, and wearable flexible devices. Herein, a series of photoresponsive self‐healing gels based on dynamic imine bonds are synthesized in which the photoresponsive functions are achieved by the incorporation of the chromophore 1,2‐bis(5′‐formyl‐2′‐methylthien‐3′‐yl)perfluorocyclopentene (DEA) and the fluorophore 2,5‐dimethoxybenzene‐1,4‐diformaldehyde derivatives (DBD) through the Schiff base reactions between DEA/DBD and aminopropylmethylsiloxane‐dimethylsiloxane copolymers. The gels show ultrafast photoresponsive ability with the transition from yellow to blue within 10 s under 254 nm UV–Vis and subsequent color restoration within 20 s under visible light, derived from the fast ring‐closure and ‐opening transition of DEA. Interestingly, the molecular states of DEA have influence on the on–off intensity of the fluorescence. The gels with ring‐opened DEA show stronger blue fluorescence than the ones with ring‐closed DEA. In addition, the cross‐linked dynamic imine bond enables the gels to self‐heal quickly, and the wound disappears within 10 min without any external stimuli.

Enhanced crystallinity and photoluminescence properties of Yb2+ doped SrSi2O2N2 phosphor for image storage applications

A series of Yb2+ and Dy3+ doped SrSi2O2N2 phosphors with enhanced crystallinity and photoluminescence properties have been successfully synthesized by two-step method using Sr2SiO4 as precursor. It is clearly indicated from XRD results that Yb2+ ions can substitute Sr sites in SrSi2O2N2 crystal and exhibit pure phase and well-crystalline in comparison with the samples prepared by traditional solid-state reaction. The excessive amount of Si3N4 in the reactants promoted the formation of pure SrSi2O2N2 phosphors phase. SrSi2O2N2: Yb2+ phosphors show emission band at 583 nm and the broad excitation peaks located at 308 nm, 384 nm and 447 nm, covering the emission wavelength of NUV and blue chips. Compared with the sample prepared by traditional one-step solid-state reaction method, a dramatic enhancement of photoluminescence emission intensity (∼1.75 times) can be observed for SrSi2O2N2: 0.01 Yb2+ phosphor synthesized by two-step method. Due to the concentration quenching, the luminescence intensity reaches the maximum when doping concentration of Yb2+ ions is 1 mol%, which is identified as the electric dipole-electric dipole interaction. Notably, Yb2+ and Dy3+ co-doped SrSi2O2N2 phosphors with pure phase exhibit a unique thermal-stimulated luminescence property under NUV excitation, indicating the potential application in optical information storage. Furthermore, the mechanism of thermal-stimulated luminescence has been proposed.

Rationally designed small molecular photoswitches based on the ESIPT mechanism of salicylaldehyde hydrazone derivatives

Organic photoswitches show significant and reversible changes of color and optical properties under the action of light, which has attracted extensive attentions due to their application prospects in the fields of optical information storage, decorative and protective packaging materials, optical device materials, photocatalysis and bioscience. Herein, a series of small organic photoswitches based on salicylaldehyde hydrazone derivatives were synthesized. They have very simple molecular structures but exhibited good photochromic properties of UV–Vis absorption and fluorescence spectra under the irradiation with 365 nm ultraviolet light. And the substituents and solvents have important effects on the photochromic properties of the resulting photoswitches. This work may provide an alternative scheme for development of photochromic materials.

Near‐Infrared Persistent Luminescence and Trap Reshuffling in Mn4+ Doped Alkali‐Earth Metal Tungstates

AbstractNear‐infrared persistent luminescent materials have great potential for in vivo bioimaging and night‐vision surveillance due to their long‐lasting autofluorescence‐free emission through deep tissues and multicycle photostimulated luminescence by releasing energy from captured traps using high‐intensity 808 or 980 nm lasers. However, phosphors combining both near‐infrared persistent luminescence and photostimulated luminescence are found mostly in chromium doped gallates hosts, other emitters are rarely reported. Herein, a new material system with near‐infrared persistent luminescence is achieved in tetravalent manganese doped double‐perovskite alkali‐earth metal tungstates via the aliovalent substitution of calcium ions with lanthanum ions. Persistent luminescence can be generated via X‐ray irradiation, providing great promise in long‐term deep‐tissue ultrasensitive imaging, information storage, and X‐ray detection. Photostimulated detrapping is successfully demonstrated using a common 420 nm light emitting diode instead of a high‐intensity 808 or 980 nm laser. The traps distribution is proved to be reshuffled upon this laser‐free visible light stimulation. Reshuffling of trap distributions upon visible light stimulation may be promising for optical information storage applications. This work is expected to broaden the range of near‐infrared persistent material systems and provides new insights into manipulating photostimulated traps via laser‐free light stimulation.

Structure and luminescence properties of Ce3+-activated BaLu2Al2Ga2SiO12 persistent phosphors for optical information storage

A novel BaLu2Al2Ga2SiO12:Ce3+ persistent phosphor was designed and synthesized through hetero-valence substituting Ba2+-Si4+ ion pair for Lu3+-Al3+ one in the Lu3Al3Ga2O12. XRD and Rietveld refinement results confirm the garnet typed crystal structure. SEM information shows that the constituent elements are uniformly distributed on the irregular particles. Under 360 or 430 nm excitation, the samples exhibit broad emission bands peaking at 510 nm. The luminescence intensity reaches to the maximum at 6 mol% Ce3+ doping content, and an internal quantum efficiency of 51.2% is achieved. The concentration quenching between Ce3+ ions is mainly originated from exchange interaction. Moreover, the phosphors exhibit bright cyan afterglow for minutes after removing the blue-light excitation source. The persistent luminescence decay process is studied by thermoluminescence spectra. The persistent luminescence mechanism and optical information writing and reading process are also discussed to explore the application in optical information storage.

Metasurface-Based Holographic Display With All-Dielectric Meta-Axilens

In a classical metasurface-based holographic display system, a clear holographic reconstruction image can be obtained only in the back-focal-plane of the lens. However, when the receiving plane deviates from the focal plane, the reconstructed holographic image suffers from degradations that limit the quality of the images. Hence, we propose a novel metasurface-based holographic display to realize clearly continuous imaging within the specified position range by superimposing the meta-axilens phase. It can effectively relieve the alignment requirements of the imaging system. Firstly, the parameters and properties of all-dielectric meta-atom is analyzed. Then we compare and demonstrate two sets of metasurface-based optical elements (meta-axicon, meta-lens, and meta-axilens), made by silicon meta-atoms working at 610 nm. Furthermore, we show that the metasurface hologram with the axilens phase can form a series of the relatively clear holographic images away from the focal plane. Our proposal suggests a method to reconstruct holographic wavefront in different planes simultaneously, and one can find their application domain, such as 3D biological imaging, spectroscopy, optical information storage, and encryption.

Light-triggered reversible supramolecular self-assembly of azo groups-functionalized copper nanoclusters

Metal nanoclusters (NCs) have attracted much attention due to their ultrasmall sizes and unique electronic structures. In recent years, the light-induced reversible assembly of Au NCs is already reported. However, to achieve light-triggered reversible self-assembly of Cu NCs is still challenging. Herein, we prepared photoresponsive Cu NCs by using an azo-containing ligand, i.e., 3,5-dimethyl-4-(phenyldiazenyl)-1H-pyrazole) (abbreviated to Hazopz). Each nanocluster contains three Cu(I) in the core and has atomic precision (denoted as Cu3-NCs hereafter). Self-assembly of Cu3-NCs into nanofibers occurred in binary solvent mixture with toluene as a good solvent and methanol (MeOH) as a poor one. When the suspension containing the nanofibers was irradiated by UV light, the originally straight nanofibers became bent. This morphological change is mainly due to the isomerization of the peripheral azo groups of the Cu3-NCs from trans- to cis-conformation, and to a small extent ascribed to the increased solubility of the cis-conformation of the azo groups in the binary solvent. The disassembled aggregates can reassemble and the bent nanofibers can become straight again when exposed to visible light. This process can be repeated for at least three times, indicating the high reversibility of this light-triggered morphological change of Cu3-NCs. The one-dimensional self-assemblies with light-triggered, reversible morphological changes achieved in this work can be potentially used as a medium material in an optical information storage device, and can write and erase information through the irradiation of UV light and visible light.