Optical Data Storage Research Articles

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.

Electrically tunable large aperture liquid crystal lens with dual hole-patterned electrodes

An electrically tunable large aperture liquid crystal (LALC) lens consisting of dual hole-patterned electrodes with different diameters is demonstrated. The proposed LALC lens can realize a tunable focal length and a switchable optical aperture by changing the driving models (DM). The experimental results show that the focal length of the LALC lens ranges from 325 mm to 220 mm when the operating voltage is changed from 24 V to 66 V by DM1, and it varies from 310 mm to 200 mm with the supplied voltages of 24–59 V by DM2. The optical aperture of the LALC lens can be switched between 4 mm-diameter and 5 mm-diameter. Furthermore, the turn-on time is significantly decreased by the over-driving method. Because of its low root mean square (RMS) error (<0.08 λ), the LALC lens, as an ideal optical lens, can exhibit excellent imaging performance in the optical imaging system. These results demonstrate that the proposed LALC lens has potential applications in the fields of imaging, biometrics and optical data storage because of its tunable focal length and switchable optical apertures.

Integrated Hybrid VO2–Silicon Optical Memory

Vanadium dioxide (VO2) is an interesting material for hybrid photonic integrated devices due to its insulator–metal phase transition. Utilizing the hysteresis of the phase transition in voltage-biased VO2, we demonstrate a compact hybrid VO2–silicon optical memory element integrated into a silicon waveguide. An optical pulse writes the VO2 memory, leading to an optical attenuation that can be read out by the optical transmission in a silicon waveguide. Our on-chip memory cell can be optically written with energy as low as 23.5 pJ per pulse and with a 10–90% rise time of ∼100 ns. This approach is promising for optical data storage in silicon photonic integrated circuits.

Photo-processing of perovskites: current research status and challenges

The past two decades have seen a drastic progress in the development of semiconducting metal-halide perovskites (MHPs) from both the fundamentally scientific and technological points of view. The excellent optoelectronic properties and device performance make perovskites very attractive to the researchers in materials, physics, chemistry and so on. To fully explore the potential of perovskites in the applications, various techniques have been demonstrated to synthesize perovskites, modify their structures, and create patterns and devices. Among them, photo-processing has been revealed to be a facile and general technique to achieve these aims. In this review, we discuss the mechanisms of photo-processing of perovskites and summarize the recent progress in the photo-processing of perovskites for synthesis, patterning, ion exchange, phase transition, assembly, and ion migration and redistribution. The applications of photo-processed perovskites in photovoltaic devices, lasers, photodetectors, light-emitting diodes (LEDs), and optical data storage and encryption are also discussed. Finally, we provide an outlook on photo-processing of perovskites and propose the promising directions for future researches. This review is of significance to the researches and applications of perovskites and also to uncover new views on the light-matter interactions.

Phototriggered color modulation of perovskite nanoparticles for high density optical data storage.

Photoresponsive luminescent materials (PLMs) have attracted much attention in various optoelectronic fields, especially in optical data storage. Multi-wavelength (N-wavelength) based optical storage is a promising approach to increase the data storage density, but its current application is limited by the fact that most PLMs have only two-wavelength emissive states after certain light excitation, which requires simultaneous use of several PLMs and different irradiation light sources. In this study, we discovered that the wavelength of perovskite nanocrystals (PNCs) in the presence of dichloromethane (DCM) could be continuously and precisely tuned over a very wide color range (from red to violet) with the help of a single UV light source. The changes in crystal structures and optical properties of PNCs during UV irradiation were investigated in detail; the effects of capping ligand, solvent, UV irradiation power and time were evaluated, and the mechanism of UV triggered PNC fluorescence change was studied and is discussed. Finally, the applicability of PNCs/DCM film in N-wavelength-based high-density optical data storage was verified.

A Datum Schemes Based on TOC Monitoring System

Abstract Using the giant parallelism of photons to develop a new type of computer with more processor bits and data, the ternary optical computer, with the birth of the ternary optical computer SD 16 physical machine, the team built a monitoring system structure for task management, It is mainly used to deal with various complex data problems and provide parallel services for computing requests of multiple users. The storage of data in the monitoring system has also become a crucial issue. Based on the existing achievements of the team, this paper designs a data storage scheme for the management software of the ternary optical computer monitoring system, and finally summarizes and looks forward to the next research direction of the ternary optical computer data storage.

Luminescence, energy transfer, colour modulation and up-conversion mechanisms of Yb3+, Tm3+ and Ho3+ co-doped Y6MoO12.

A series of novel up-conversion luminescent Yb3+/Ln3+ (Tm3+, Ho3+, Tm3+/Ho3+)-doped Y6MoO12 (YMO) nanocrystals were synthesized using the sol-gel method. The consistent spherical morphology of the nanocrystals with different doping ratios was found to be profiting from the homogenisation and rapid agglomeration of the composition in the gel state and calcining process. The X-ray diffraction (XRD) and field-emission scanning electron microscope images were employed to confirm perfect crystallinity and uniform morphology. Photoluminescence spectra and decay curves were used to characterize the optical properties of the synthesized samples. The YMO:Yb3+/Ln3+ (Tm3+, Ho3+, Tm3+/Ho3+) nanocrystals were excited by near-infrared photons and emitted photons distributed in blue, green, and red bands with a wide colour gamut, and even white colour, by optimising the relative doping concentrations of the activator ions. The energy conversion mechanism in the up-conversion process was studied using power-dependent luminescence and is depicted in the energy level diagram. In addition, 70% of the luminescence intensity of YMO can be preserved after annealing at 700 °C, and the temperature sensing was tested in the range 298-498 K. These merits of multicolour emissions in the visible region and good stability endow the as-prepared nanocrystals with potential applications in the fields of optical data storage, encryption, sensing, and other multifunctional photonic technologies.

Sc dopant induced tailoring of persistent luminescence in Na3YSi3O9:Eu2+ for information recording

A novel green afterglow Na3(Y,Sc)Si3O9:Eu2+ phosphor is synthesized for optical data storage and latent fingerprint recognition.

Reversible Mn valence state switching in submicron α-Al2O3:Mn by soft X-rays and blue light - a potential pathway towards multilevel optical data storage.

The generation of Mn4+ in α-Al2O3:Mn3+ by soft X-ray exposure is demonstrated with a large dynamic range of the X-ray generated Mn4+ luminescence signal, indicating the potential use of α-Al2O3:Mn3+ for multilevel optical data storage. Samples with a range of Mn concentrations (0.05, 0.1, 0.2, 0.4, 0.6 and 1.2 atom%) were prepared via a facile combustion method and the sample with 0.4 atom% was found to display the highest luminescence intensity. The stored information can be read out via the R-lines (2E → 4A2) under ∼470 nm (4A2 → 4T2), or ∼630 nm (4A2 → 2T1) excitation with the latter being preferred since photobleaching is minimized. Interestingly, the Mn4+ valence state can be fully switched back to Mn3+ by blue light exposure (e.g., 462 nm laser diode). The stored information could be repeatedly written and erased, showing no significant deterioration over five consecutive cycles, with less than 5% uncertainty.

Bi-directional photonic switch and optical data storage in a hybrid optomechanical system

We propose to achieve quantum optical nonreciprocity in a hybrid qubit-optomechanical solid-state system. A two-level system (qubit) is coupled to a mechanically compliant mirror (via the linear Jaynes–Cummings interaction) placed in the middle of a solid-state optical cavity. We show for the first time that the generated optical bistability exhibits a bi-directional photonic switch, making the device a suitable candidate for a duplex communication system. On further exploring the fluctuation dynamics of the system, we found that the proposed device breaks the symmetry between forward and backward propagating optical modes (optical nonreciprocity), which can be controlled by tuning the various system parameters, including the qubit, which emerges as a new handle. The device thus behaves like an optical isolator and hence can store optical data in the acoustic mode, which can be retrieved later.

Design and analysis of an InGaAs/InGaAsP quantum well microlaser with longitudinal periodical strain distribution for single-mode lasing.

Single-mode lasing for small size semiconductor laser is significantly important in the on-chip optical signal processing, data storage, and dense optical integrated systems. This paper presents new, to the best of our knowledge, single-mode quantum well microlasers by distributing periodical strain along the longitudinal laser cavity. The quantum transmission line modeling (Q-TLM) method is employed to establish the model for strained microlasers. The dynamic output of quantum well microlasers with longitudinal periodical strain (LPS) distribution is analyzed in the time and frequency domains, and it is found that the introduction of LPS significantly improves the single-mode output of quantum well microlasers by increasing the side mode suppression ratio (SMSR) from 8.44 to 28.29 dB. The study results confirm that well-controlled periodical strain along the longitudinal laser cavity provides an alternative routine for realizing single-mode lasing by strain engineering.

A Review on Physical and Optical Properties of Zinc Tellurite Glasses Co-doped with different rare earth ions

In this work we review the effect of physical and optical properties with different ion zinc contents of tellurite base glass. The physical properties of the glasses were evaluated and the change in density, molar volume and ionic packing density in these glasses indicates the effect of ZnO different content show on the glasses structure. The study of optical properties such as the optical band gap and refractive index of zinc tellurite glass were studied. Zinc Tellurite glasses doped with Er3+ ions were synthesized by varies researcher. The glasses were characterized by X- ray diffraction, optical absorption and photoluminescence spectra. The glassy nature of zinc Tellurite host glass has been confirmed through XRD measurements. The glasses doped or co-doped with rare-earth ions have generated much interest due to the possibility of several promising applications such as optical data storage, visible laser, fibre amplifier, optical communication and sensor devices

Near‐Field Mediated 40 nm In‐Volume Glass Fabrication by Femtosecond Laser

AbstractNanofabrication techniques have significantly impelled the development of nanomechanics and nanophotonics by making nano‐precision material processing routine. Although widely employed, current sub‐100 nm nanofabrication approaches based on focused particles or light are limited to surface modification. Here, an optical in‐volume fabrication approach that enables 3D glass processing with a spatial resolution down to 40 nm is demonstrated. Such an approach is based on the formation of a single nanoslit structure induced by femtosecond laser pulses. Spatially‐variant nanopatterns with uniform line‐widths are then formed by a near‐field mediated intensity redistribution of incident light. The redistribution of electromagnetic field induced by the presence of the nanoslit leads to a positive‐feedback self‐assembly process. The self‐assembly process allows achieving spacing one order of magnitude smaller than the laser beam size. In addition, a tilted ablation front that results in the generation of structures with curved morphology is revealed. The proposed approach enables 3D patterning with a lateral spacing down to 200 nm and 5D optical data storage with an equivalent capacity of 7.2 TB per disk, demonstrating its feasibility for 3D nanoscale processing in bulk materials.

Sharper photonic nanojets generated by microspheres under higher-order radially polarized beam illumination.

Photonic nanojets (PNJs) generated from a single microsphere illuminated by higher-order radially polarized (RP) beams are investigated. The effects of the size parameters of higher-order RP beams, the refractive index, and radius of the dielectric microsphere on the full width at half-maximum and peak intensity of the PNJ are numerically discussed and qualitatively interpreted. The results show that the minimal width of the PNJ can be obtained by optimally adjusting the size parameter. The PNJ beam waist becomes gradually narrower with increasing the radial mode number. As compared to the case of plane wave illumination, sharper PNJs are more easily generated when irradiated by a higher-order RP beam, even for microspheres with lower refractive indices or larger radii. Our findings can promote potential applications of PNJs in a variety of fields including super-resolution microscopy, nanolithography, and optical data storage.

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.

Machine learning holds promise for optimizing optical data storage technology

Applications in image analysis, guiding adaptive optics and targeted design, look to push new storage techniques even further.

Light-patterned fluorescent gold nanoclusters in polycarbonate films

Fluorescent metal nanoclusters embedded in rigid matrices are attractive for many applications, such as for use as light-emitting diodes and for optical data storage. Given the advantages of polycarbonate films, like high transparency and excellent toughness, the development of metal nanoclusters in these films could further enhance various applications. Herein, we fabricated fluorescent gold nanoclusters in a polycarbonate film using a photochemical process. The polymer film is doped with gold chloride and a photoinitiator and then irradiated by a light-emitting diode (365 nm), leading to the photoreduction of gold ions and the formation of bright fluorescent nanoclusters with a quantum yield of 15%. The as-formed nanoclusters display good photostability and retain their emission spectral shape over an extended period of time. These highly fluorescent structures have potential applications in the fabrication of authenticity markings and optoelectronic devices.

Efficient dynamic control method of light polarization using single phase-only liquid crystal on silicon spatial light modulators for optical data storage.

The technology of five-dimensional (5D) optical data storage in transparent materials paves a promising way to unlimited lifetime data storage for future cloud use. Phase-only liquid-crystal-on-silicon spatial light modulators (LCOS SLMs) have already exhibited its potential for this application in tailoring ultrafast laser writing beams for 5D optical data storage. A phase-only LCOS SLM can generate arbitrary data patterns by using diffractive holographic imaging for data writing light beam generation. However, the polarization control of the output holographic image is still achieved by using an external polarization modulator, which leads to complications, bulkiness, and large delays in current methods. In this paper, we presented an efficient phase and polarization modulation method through a compact system based on a single phase-only LCOS SLM to simultaneously control both the holographic image and its polarization state. The proposed method utilizes two-polarization-component coding in conjunction with a polarization component rotation technique in a compact system. Using this polarization rotation technique, two light components can be independently coded by separately using two holograms on two halves of the LCOS SLM. We experimentally construct a proof-of-concept prototype of the compact system, and the effectiveness of the system has been experimentally verified.

Nanophotonics-enabled optical data storage in the age of machine learning

The growing data availability has accelerated the rise of data-driven and data-intensive technologies, such as machine learning, a subclass of artificial intelligence technology. Because the volume of data is expanding rapidly, new and improved data storage methods are necessary. Advances in nanophotonics have enabled the creation of disruptive optical data storage techniques and media capable of storing petabytes of data on a single optical disk. However, the needs for high-capacity, long-term, robust, and reliable optical data storage necessitate breakthrough advances in existing optical devices to enable future developments of artificial intelligence technology. Machine learning, which employs computer algorithms capable of self-improvement via experience and data usage, has proven an unrivaled tool to detect and forecast data patterns and decode and extract information from images. Furthermore, machine learning has been combined with physical and chemical sciences to build new fundamental principles and media. The integration of nanophotonics-enabled optical data storage with emerging machine learning technologies promises new methods for high-resolution, accurate, fast, and robust optical data writing and reading, as well as the discovery, design, and optimization of nanomaterials and nanostructures with new functionalities for next-generation nanophotonics-enabled optical data storage. In this Perspective, we review advances in nanophotonics-enabled optical data storage and discuss the role of machine learning in next-generation nanophotonics-enabled optical data storage.

Preparation and application of multi-wavelength-regulated multi-state photoswitchable fluorescent polymer nanoparticles

The photoswitchable system with color and multi-state fluorescence changes is the key to the realization of advanced multi-level information storage, and its application potential has far exceeded the monochromatic fluorescent system. Herein, we introduced a novel multi-state photoswitchable fluorescent polymeric nanoparticles, which contains two energy-matched photoswitchable fluorescent molecules, i.e. diarylethene derivative (BH, donor) and spiropyran derivative (SPMA, acceptor), to construct a tunable fluorescence resonance energy transfer (FRET) system. By optimizing the feeding ratio of the two photochromic molecules to control the efficiency of energy transfer, the fluorescence of the nanoparticles can be reversibly switched among none, red, orange, and green by adjusting the wavelength of light stimuli. In addition, the nanoparticles display good water dispersibility, high brightness, fast responsiveness, excellent photoreversibility, and long-term fluorescence stability. We also verified that the system has great potential in optical data storage, multi-layer information encryption, and anti-counterfeiting.