Optical Data Storage Applications Research Articles

Linear charging-discharging of an ultralong UVA persistent phosphor for advanced optical data storage and wide-wavelength-range detector

Ultraviolet persistent luminescence (UV PersL) phosphor is currently gaining considerable attention due to its promising potential for widespread advanced applications. However, the linear manipulation of electron charging-discharging and the prolongation of persistent time remains a huge challenge. Here, we report a novel Bi3+ doped Mg2GeO4 UVA PersL phosphor via a nonequivalent substitution strategy. The UVA PersL performance of Mg2GeO4:Bi3+ is significantly improved by introducing Li+ ions, yielding a superior UVA PersL property with afterglow lasting time beyond 100 h. The trap distribution management and the captured electron motion dynamics are revealed by the thermoluminescence technique under various external stimuli. Moreover, UVA PersL can be repeatedly rejuvenated by NIR and blue LED stimulation owing to the optically stimulated electrons from different depth traps to shallow traps. Due to the invisibility of UVA light, barcode information stored on the phosphor film can be read by NIR light and then erased by blue light, exhibiting the potential application in optical data storage with good concealment and security. Most remarkable is the electron charging-discharging linear functions of the irradiated power of UV, and blue and NIR light which was never reported, providing a feasible approach for optical power detection in a wide-wavelength-range. This work not only offers a guideline to develop novel high-performance UV PersL materials but also provides a route to effectively manipulate the electrons in the traps toward applications in advanced optical information storage and wide-wavelength-range light detection.

Organic Near‐Infrared Luminescent Materials Based on Excited State Intramolecular Proton Transfer Process†

Comprehensive SummaryOrganic near‐infrared (NIR) luminescent materials have captured intense research interest owing to their potential applications in optical communication, data storage, bioimaging, sensing and night vision. Excited state intramolecular proton transfer (ESIPT) process with absorption in normal form while emission in tautomer form can lead to a distinct redshift emission, based on which, a lot of organic NIR luminescent materials were designed. Because of attractive features such as ultrahigh sensitivity to the surroundings, large Stokes shift, and inherent four level system, ESIPT based NIR luminescent materials are supposed to be ideal fluorescent probes and gain materials. In this review, first, organic near‐infrared luminescent materials based on ESIPT process are summarized according to the core structures. Second, recent advances of ESIPT‐based organic near‐infrared fluorescent probes and organic NIR lasers are reviewed. Finally, the current challenges and prospects of ESIPT‐based organic NIR luminescent materials are introduced.

Better colloidal lithography: Tilt-rotate evaporation overcomes the limits of plasma etching

Colloidal lithography (CL) is a promising method for large-area fabrication of nanohole and nanodot arrays with applications in optical biosensing, separations, and magnetic data storage. However, reducing the diameter of the polystyrene sphere mask by plasma etching unavoidably increases their coefficient of variation (CV) and deforms their shape, thereby limiting the pitch-to-hole-diameter ratio of the resulting nanohole array to less than 3:1 and the minimum hole size to 200 nm with a 10% or better CV. We show that tilt-rotate evaporation colloidal lithography (TRE-CL) breaks the trade-off between hole diameter and polydispersity by leveraging glancing angle evaporation, not plasma etching, to adjust the hole size. TRE-CL allows pitch-to-hole-diameter ratios as high as 7:1 and nanohole diameters down to 60 nm while maintaining a nearly constant CV below 10% and hole circularity above 91%. We transfer these hole arrays into ultrathin Si3N4 films to form nearly-monodisperse microsieves for separation applications. Furthermore, we extend TRE-CL to fabricate adhesion-layer-free plasmonic Au nanodot arrays down to 70 nm in diameter with 10% CV.

Ultraviolet C random lasing at 230–280 nm from Pr3+ doped bulk crystal resonators by two-photon absorption

Ultraviolet solid-state light sources, especially in the short-wave ultraviolet band, are attracting great attention for potential applications in high-density optical data storage, biomedical research, and water and air purification and sterilization. As one of the means to generate solid-state short-wavelength lasers, upconversion technology, which can transform a low-energy photon to a high-energy photon, has a simple structure and does not require strict phase-matching conditions. However, because of the high non-radiative decay rate during multiphoton absorption process, the short-wave upconversion ultraviolet lasing is still difficult to achieve. Here, under 450 nm blue laser excitation, we have successfully obtained ultraviolet C random lasing from a Pr3+ doped YPO4 single crystal via two-photon absorption. Presently, ultraviolet C random lasing with the wavelength range of 230–280 nm is the shortest wavelength for upconversion lasing emission.

Carrier mobility in field effect transistors based on copper-phthalocyanine thin films with different phase structure

Using annealing procedure at different temperatures after deposition at room temperature we obtained copper- phthalocyanine (CuPc) thin films with a — and p —phase structure. A phase structure of thin films was controlled by X-ray diffraction method, morphology was controlled by SEM. The field effect transistors was fabricated by high vacuum deposition of CuPc thin film (thickhess of 100 nm) on Si02 substrate which acting as gate contact. Gold drain and source contacts deposited on the top of active layer of FET. From measured current voltage measurements calculated mobility and concentration of charge carriers in FET. These parameters depend on phase structure of CuPc thin film, and characteristics of our FET are comparable with values of other authors.
 CuPc is commercially available macro cyclic metal complex that can be easily obtained in large quantity and high purity. Together with other phthalocyanine derivatives, the chemically and thermally stable CuPc has wide applications in dye processing, spectral sensitization, chemical sensors, and optical data storage [3-4]. The semiconducting behavior of metal phthalocyanines was first observed in 1948 and they have since attracted great interest in advancement of protptype organic semiconductors. Among the metal substituted phthalocyanines CuPc has been found superior properties [5-7], such as phenomena of field dependent and wavelength-dependent efficiency in an organic static induction transistors, and stabilizing role of CuPc layer on a highly stable organic electroluminescent device based on thin film Alq, and indicated a very weak interaction between CuPc and Au at the interface.
 In general, phthalocyanine materials can exist in several crystalline polymorphs, including a-, p -, x-and y - structure, and the most well known are the thermally metastable a- and p - [8-10], Phthalocyanine films deposited at room temperature usually consist of a-phase crystallites (at sublimation pressure of less than 10 Pa). At higher deposition pressures or at substrate temperature above 210°C, the p -phase directly obtained [11], Although it is well known that a-phase crystallites undergo a phase transformation into P -phase by treatment in various organic suspension media [12,13] or during annealing at higher temperatures [14,15], only some authors describe the nature of the a—>p phase transformation of copper phthalocyanine thin films with a thickness of less than 100 nm [8,14-15].

Theoretical Study on Generation of Multidimensional Focused and Vector Vortex Beams via All-Dielectric Spin-Multiplexed Metasurface.

The optical vortex (OV) beams characterized by orbital angular momentum (OAM) possess ubiquitous applications in optical communication and nanoparticle manipulation. Particularly, the vortex vector beams are important in classical physics and quantum sciences. Here, based on an all-dielectric transmission metasurface platform, we demonstrate a spin-multiplexed metadevice combining propagation phase and Pancharatnam–Berry (PB) phase. By utilizing a phase-only modulation method, the metadevice can generate spin-dependent and multidimensional focused optical vortex (FOV) under the orthogonally circularly polarized incident light, and it can successfully realize the multiplexed of the above-mentioned FOVs for linearly polarized light. Meanwhile, the superposition of multiple OAM states can also produce vector vortex beams with different modes. Additionally, the evolution process of the electric field intensity profile is presented after the resultant vector vortex beams through a horizontal linear polarization. This work paves an innovative way for generating structured beams, and it provides promising opportunities for advanced applications in optical data storage, optical micromanipulation, and data communication.

Multi-freedom metasurface empowered vectorial holography

Abstract Optical holography capable of the complete recording and reconstruction of light’s wavefront, plays significant roles on interferometry, microscopy, imaging, data storage, and three-dimensional displaying. Conventional holography treats light as scalar field with only phase and intensity dimensions, leaving the polarization information entirely neglected. Benefiting from the multiple degrees of freedom (DOFs) for optical field manipulation provided by the metasurface, vectorial holography with further versatile control in both polarization states and spatial distributions, greatly extended the scope of holography. As full vectorial nature of light field has been considered, the information carried out by light has dramatically increased, promising for novel photonic applications with high performance and multifarious functionalities. This review will focus on recent advances on vectorial holography empowered by multiple DOFs metasurfaces. Interleaved multi-atom approach is first introduced to construct vectorial holograms with spatially discrete polarization distributions, followed by the versatile vectorial holograms with continuous polarizations that are designed usually by modified iterative algorithms. We next discuss advances with further spectral response, leading to vivid full-color vectorial holography; and the combination between the far-field vectorial wavefront shaping enabled by vectorial holography and the near-field nano-printing functionalities by further exploiting local polarization and structure color responses of the meta-atom. The development of vectorial holography provides new avenues for compact multi-functional photonic devices, potentially useful in optical encryption, anticounterfeiting, and data storage applications.

Focusing of radially polarized bessel gaussian and hollow gaussian beam of high NA to achieve super resolution

To achieve super-resolution, a radially polarized Bessel Gaussian and a Hollow Gaussian Beam with high NA are focused. For both Bessel Gaussian and Hollow Gaussian Beams with high numerical aperture NA, the radially polarized component with two equal-intensity peaks covers 25% of the total intensity, while the longitudinally polarized component covers the rest. By focusing radially polarized Bessel and Hollow Gaussian beams, it is possible to generate various focal spots with different dimensions that are applicable for various applications in optical trapping, data storage, biomedical imaging, laser cutting, material processing, and microscopy. The effects of various Bessel beam characteristics are investigated. It was found that the beam radius reaches a minimum at a specified starting beam radius for all propagation distances and that the optimum starting beam radius is also large at long propagation distances. This findings are of great significance in optical trapping, data storage, biomedical imaging, and laser cutting.

Reversible Photochromic Coordination Polymer by Phototriggered Subtle Molecular Conformation Variations.

Photochromic materials are constructed with molecules accompanied by structural change after triggering by light, which are of great importance and necessity for various applications. However, because of space-confinement effects, molecule stacking of these photoresponsive chromophores within coordination polymers (CPs) always results in an efficiency decrement and a response delay, and this phenomenon will lead to a poor photochromic property. Herein, a CP (named CIT-E) with a 3-fold-interpenetrating network structure, which was prepared with (Z)-1,2-diphenyl-1,2-bis[4-(pyridin-3-ylmethoxy)phenyl]ethene (1Z) and a CuI cluster, showed fast reversible photochromic behavior. Under UV-light illumination, the color of CIT-Z changed from pale yellow to reddish brown. With the illumination of green light, the polymer could return to its initial color within 10 s. To reveal the mechanism of reversible photochromic behavior of CIT-Z, single-crystal structures of each color state were fully studied, and other scientific study methods were also used, such as time-dependent density functional theory calculation and control experiments. It was found that, with light illumination, this behavior of CIT-Z was the result of a ligand-to-metal charge-transfer process, and this process was triggered by subtle molecular conformation variation of tetraphenylethylene. It should be noted that CIT-Z has high thermal and chemical stability, which are excellent advantages as smart photoresponsive materials. As a proof of concept, a uniform thin film with such a fascinating photochromic property allows applications in invisible anticounterfeiting and dynamic optical data storage. Overall, the present study opens up a new avenue toward reversible photochromic materials.

Anisotropic nanostructure generated by a spatial-temporal manipulated picosecond pulse for multidimensional optical data storage.

Anisotropic nanostructures can be generated in fused silica glass by manipulating the spatiotemporal properties of a picosecond pulse. This phenomenon is attributed to laser-induced interband self-trapped excitons. The anisotropic structures exhibit birefringent properties, and thus can be employed for multi-dimensional optical data storage applications. Data voxels generated by such short laser irradiation enable on-the-fly high-speed data recording.

Synaptic Plasticity Powering Long-Afterglow Organic Light-Emitting Transistors.

Long-lasting luminescence in optoelectronic devices is highly sought after for applications in optical data storage and display technology. While in light-emitting diodes this is achieved by exploiting long-afterglow organic materials as active components, such a strategy has never been pursued in light-emitting transistors, which are still rather unexplored and whose technological potential is yet to be demonstrated. Herein, the fabrication of long-afterglow organic light-emitting transistors (LAOLETs) is reported whose operation relies on an unprecedented strategy based on a photoinduced synaptic effect in an inorganic indium-gallium-zinc-oxide (IGZO) semiconducting channel layer, to power a persistent electroluminescence in organic light-emitting materials. Oxygen vacancies in the IGZO layer, produced by irradiation at λ= 312nm, free electrons in excess yielding to a channel conductance increase. Due to the slow recombination kinetics of photogenerated electrons to oxygen vacancies in the channel layer, the organic material can be fueled by postsynaptic current and displays a long-lived light-emission (hundreds of seconds) after ceasing UV irradiation. As a proof-of-concept, the LAOLETs are integrated in active-matrix light-emitting arrays operating as visual UV sensors capable of long-lifetime green-light emission in the irradiated regions.

Up-conversion luminescence regulation and its boosting by polarization in Er3+/Yb3+ doped SrBi8Ti7O27 photochromic ceramics for optical switching application

The various applications of luminescence materials were generally based on the effective modulation of luminescence spectra. However, the research on reversible spectral regulation of up-conversion (UC) luminescence materials was still in its infancy stage. In this work, a class of smart phosphor, Er3+ and Yb3+-codoped SrBi8Ti7O27 (SBYT: xEr3+) intergrowth bismuth layer-structured ferroelectric, possessing fast sensitivity to visible light irradiation, was reported based on visible light driven photochromic effect. Through the alternate stimuli of light irradiation and heating treatment, the reversible regulation of UC luminescence was achieved accompanying with the switching of coloration and decoloration processes. The luminescence modulation degree tightly relied on the irradiation time and thermal treatment modes. The reversibility and stability properties were also revealed. Moreover, it is found that polarization treatment was an effective approach which can be adopted to improve the UC luminescence contrast. The maximum luminescence modulation ability of SBYT: xEr3+ reached up to 81.3% which was 131% of that un-polarized sample. It is believed that SBYT: xEr3+ ceramics can act as a promising candidate for optical data storage and anti-counterfeiting applications.

Selective Excitation of Polarization‐Steered Chiral Photoluminescence in Single Plasmonic Nanohelicoids

AbstractThe development of chiral photoluminescence (PL) has drawn extensive attention owing to its potential applications in optical data storage, biosensing, and displays. Due to the lack of effective synthesis methods, colloidal metal nanostructures with intrinsic chiral PL have rarely been reported. Herein, the chiral excitation and emission properties of single gold nanohelicoids (GNHs) are reported for the first time. By measuring their circular dichroism (CD) response and excitation/emission polarization‐resolved PL spectra, it is revealed that the intrinsic chirality arising from the geometric handedness of the GNHs induces the observed excitation‐polarization‐correlated chiral PL. Two models are developed to analyze the observed circular‐polarization‐steered effect: (1) a chiral PL phenomenological model quantitatively reproduces the PL dissymmetry features; (2) a chiral Purcell effect model reveals that the super‐chiral near fields in the GNHs account for the far‐field chiral responses such as the polarization‐steered chiral PL. The findings not only provide an important understanding of the physical mechanism responsible for luminescent chiral plasmonic nanostructures, but also expand the research on chiral PL‐active materials from achiral/chiral hybrid systems to metallic nanostructures with intrinsic structural chirality, thereby broadening the scope of applications in 3D chiral imaging and sensing as well as microstructure analysis.

The inhibition of CsPbBr3 nanocrystals glass from self-crystallization with the assistance of ZnO modulation for rewritable data storage

In the era of big data, the large amount of data generated every second requires modern and advanced data storage technologies. Femtosecond (fs) laser induced crystallization allow for the realization of fixed-point crystallization inside the CsPbBr3 nanocrystals glasses (CPB), which can be applied in data storage. However, CPB is prone to self-crystallization prior to further heat treatment, interfering with fs-induced crystallization inside the glass and seriously hindering its application in data storage. Herein, we first propose the inhibition of CPB from self-crystallization by modulating the content of ZnO (4–20 mol%) using a melt-quenching method. ZnO was employed as a network modifier and was closely related to the glass network structure. When the content of ZnO was 4%, the CPB did not self-crystallize and was colorless. It was applied in the rewritable data storage by combining the 800 nm fs laser-induced crystallization, annealing (460 ℃/0.5 h) and fs laser erasing (20 mW). This work demonstrates a simple and efficient way to control the self-crystallization of CPBs, enhancing their potential practical application in high-capacity optical data storage with ultra-long working lifetimes.

From binary to multinary copper based nitrides – Unlocking the potential of new applications

• Diversity of synthetic strategies towards copper nitrides as bulk or thin films. • Overview of conditions that allow to control the morphology and particle size. • Structural diversity of multinary copper nitrides and their emerging applications. This review summarizes the current knowledge on the chemistry of binary copper(I) nitride, Cu 3 N and its multinary derivatives containing either main group or transition metal elements. For many years, research in this area was focused on the development of copper nitride prepared in the form of thin films. Successful deposition of these materials has been achieved mainly by employing physical methods, which have provided materials suitable for potential application in optical data storage. However, for the last decade, attention has also been devoted to expanding the available options by which Cu 3 N can be synthesized and deposited. Consequently, the focus has switched to the development of chemical synthetic methods towards the fabrication of this semiconductor and to broadening the range of related compounds that might be discovered. Simultaneously, the formulation of novel techniques and the successful preparation of new nanostructured functional materials has resulted in the rapid evolution of new and relevant applications; e.g. catalytic and electrochemical. The overview presented here concentrates on the chemical methods that have been devised to synthesise both bulk samples and thin films of Cu 3 N. Our article also shows how these approaches have been developed to achieve significant progress in the creation of multinary copper based nitrides and in identifying their potential applications. It provides a concise history of previous copper nitride research and sets the context for the most current advances. These will no doubt provide the springboard for future research areas that will impact both transition metal nitride chemistry and materials science more generally.

Ultrafast Laser Inducing Continuous Periodic Crystallization in the Glass Activated via Laser‐Prepared Crystallite‐Seeds

AbstractTailoring ultrafast light–matter interaction as an enabler to create functional periodic crystalline patterns inside transparent dielectrics is of great scientific and technological significance but remains a tremendous challenge because of plenty of unclarified process details and physical mechanisms. Here, a dynamic process of ultrafast laser‐induced continuous periodic crystallization (CPC) to generate self‐organized crystal arrays (CAs) inside the glass is reported. The crystallite‐seeds induced by ultrafast laser are revealed to offer an auxiliary effect that can initiate and maintain the CPC process, which promises the high‐efficiency writing of CAs. The auxiliary effect originates from photo‐induced defects in the crystallite‐seeds, functions by drastically decreasing the pulse energy threshold for writing CAs, and can be manipulated by tuning the glass compositions and laser parameters. The created CAs are erasable and rewritable, which allows for potential applications in optical information encryption and data storage. This work not only opens up an avenue for creating embedded periodic crystalline patterns with extremely high efficiency but also helps to clarify the dynamics of ultrafast laser nanostructuring inside transparent dielectrics.

Rhenium doped Sb2Te phase change material with ultrahigh thermal stability and high speed

Sb2Te material is an important base material for phase change memory or optical data storage, but the poor amorphous stability of Sb2Te severely limits its application. In this work, we proposed a superhard and infusible Rhenium (Re) doped Sb2Te (RST) phase change material to improve the properties of Sb2Te. The data retention of RST was remarkably increased to 152 °C@10 years, which is much higher than those of traditional Ge2Sb2Te5 (87 °C@10 years) and Sb2Te (56 °C@10 years). The operation speed of the RST based device is as fast as 10 ns and the resistance ratio is more than 102 times. The density change of RST (4.2%) is smaller than those of Ge2Sb2Te5 (6.5%) and Sb2Te (5.7%). Furthermore, the operation voltage and power consumption of RST based device are much lower than those of Ge2Sb2Te5 and Sb2Te based devices. The results indicate that the RST is a promising material for high performance phase change memory or optical data storage applications.

High-contrast photochromic Eu-doped K0.5Na0.5NbO3 ceramics with prominent pellucidity.

The Eu-doped K0.5Na0.5NbO3 pellucid ceramics were first prepared via a conventional solid-state reaction, and they exhibited light illumination-induced high-contrast photochromism of both optical transmittance and photoluminescence behaviors. Through thermal treatment, the optical performances could return to their initial states and displayed excellent reversibility. Eu3+ ions were selected as the luminescent activator for detecting the local environment of the K0.5Na0.5NbO3 host. Meanwhile, the effects of the amount of Eu3+ present on phase structures, microstructures, optical transmittance and photoluminescence intensities were systematically investigated. The results suggest that Eu-doped K0.5Na0.5NbO3 transparent ceramics possess multifunctionality including photochromism, photoluminescence and optical switching properties, and that they exhibit promising potential for non-destructive optical data storage application.

Turning On Solid-State Luminescence by Phototriggered Subtle Molecular Conformation Variations.

The development of solid-state intelligent materials, in particular those showing photoresponsive luminescence (PRL), is highly desirable for their cutting-edge applications in sensors, displays, data-storage, and anti-counterfeiting, but is challenging. Few PRL materials are constructed by tethering the classic photochromic systems with newly-emerged solid-state emitters. Selective solid-state photoreactions are demanded to precisely manipulate the luminescent behavior of these emitters, which require dramatic structural change and enough free space, thus limiting the scope of the PRL family. Here, a new PRL material, TPE-4N, that features sensitive and reversible fluorescence switching is reported. The interesting on-off luminescent property of TPE-4N can be facilely tuned through fast phototriggering and thermal annealing. Experimental and theoretical investigations reveal that subtle molecular conformation variation induces the corresponding PRL behavior. The crystalline and amorphous state endows an efficient and weak ISC process, respectively, to turn on and off the emission. The readily fabricated thin-film of TPE-4N exhibits non-destructive PRL behavior with high contrast (>102 ), good light transmittance (>72.3%), and great durability and reversibility under room light for months. Remarkably, a uniform thin-film with such fascinating PRL properties allows high-tech applications in invisible anti-counterfeiting and dynamic optical data storage with micro-resolution.

Introducing and studying origin of deep electron traps in Ba1-xZrSi3O9:xEu for optical data storage

Eu ions doped Ba 1-x ZrSi 3 O 9 :xEu materials are synthesized by solid state reaction method, facing optical data storage applications. The doping of Eu ions introduces deep electron traps at 0.90 eV below the conduction band minimum of Ba 1-x ZrSi 3 O 9 :xEu (1400 °C air). Moreover, the trap distribution is tunable, and there are only deep traps in sample Ba 0·85 ZrSi 3 O 9 :0.15Eu (1400 °C Ar/H 2 ) with the disappearance of shallow traps. Deep traps can prevent information from loss, while the disappearance of shallow traps can eliminate interference to deep traps by avoiding redeployment of electrons between shallow and deep traps over time. Further, post-sintering in a reducing atmosphere after sintering in the air can increase the concentration of deep traps and deepen the color of samples, while post-sintering in the air after sintering in a reducing atmosphere can obviously decrease the concentration of deep traps and the color of samples return to white from yellow. Experimental results indicate that the deep traps in samples Ba 1-x ZrSi 3 O 9 :xEu should originate from oxygen vacancy defects, which also serve as color centers. First principles calculations show that V O1 oxygen vacancy defects introduce obvious defect energy levels below the conduction band minimum of BaZrSi 3 O 9 -V O1 , which further illustrate the deep traps should originate from V O1 oxygen vacancy defects located at the connection of layer to layer in layered matrix. Ba 1-x ZrSi 3 O 9 :xEu materials with deep electron traps are good candidates for optical data storage. • The doping of Eu ions introduces deep electron traps. • The trap distribution is tunable by atmosphere treatment. • The deep traps should originate from V O1 oxygen vacancy. • Ba 1-x ZrSi 3 O 9 :xEu materials are good candidates for optical data storage.