Two-photon excitation provides a means of activating chemical or physical processes with high spatial resolution in three dimensions and has made possible the development of three-dimensional fluorescence imaging, optical data storage, and lithographic microfabrication. These applications take advantage of the fact that the two-photon absorption probability depends quadratically on intensity, so under tight-focusing conditions, the absorption is confined at the focus to a volume of order λ3 (where λ is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume. Although three-dimensional data storage and microfabrication have been illustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems exhibit low photosensitivity as the initiators have small two-photon absorption cross-sections (δ). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new initiators have been developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical structures, including photonic-bandgap-type structures.

Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication

A review on the advancements in phosphor-converted light emitting diodes (pc-LEDs): Phosphor synthesis, device fabrication and characterization

Utilizing energy transfer (ET) between the sensitizer and acceptor in phosphors is a good way to obtain tunable emission color. Therefore, many researchers have devoted their interest to design phosphors with different emission colors via their energy transfer properties. It is well known that Ce3+ and Bi3+ are good sensitizers, while Mn2+, Dy3+, Eu3+ and Sm3+ can be useful activators. Further, Eu2+ and Tb3+ can be both good sensitizers and activators. Therefore, herein we summarise many recent ET systems consisting of Eu2+–Mn2+/Tb3+, Eu2+–Tb3+–Mn2+/Eu3+/Sm3+, Ce3+–Mn2+/Tb3+/Dy3+/Eu2+, Ce3+–Tb3+–Mn2+/Eu3+/Sm3+, Bi3+–Eu3+/Sm3+ and Tb3+–Eu3+/Sm3+, which show tunable emission color from ultraviolet to blue and green, blue to green, yellow, orange and pink/red, cyan to green, orange and pink/red, and green to yellow/orange and red. Based on this summary, this review will be a good reference to benefit the design and investigation of phosphors potentially applied in FEDs and LEDs with ET.

Recent development in phosphors with different emitting colors via energy transfer

Recent Advances in Bismuth Ion‐Doped Phosphor Materials: Structure Design, Tunable Photoluminescence Properties, and Application in White LEDs

The launch of the big data era puts forward challenges for information preservation technology, both in storage capacity and security. Herein, a brand new optical storage medium, transparent glass ceramic (TGC) embedded with photostimulated LiGa5O8: Mn2+ nanocrystals, capable of achieving bit-by-bit optical data write-in and read-out in a photon trapping/detrapping mode, is developed. The highly ordered nanostructure enables light–matter interaction with high encoding/decoding resolution and low bit error rate. Importantly, going beyond traditional 2D optical storage, the high transparency of the studied bulk medium makes 3D volumetric optical data storage (ODS) possible, which brings about the merits of expanded storage capacity and improved information security. Demonstration application confirmed the erasable–rewritable 3D storage of binary data and display items in TGC with intensity/wavelength multiplexing. The present work highlights a great leap in photostimulated material for ODS application and hopefully stimulates the development of new multi-dimensional ODS media. An optical data storage (ODS) system that is cost-effective to make and easily scalable could lay the foundations for data storage technologies with higher capacity and improved security. The era of big data is driving the need for data storage systems with larger capacity, better security and improved performance. However, even the latest two-dimensional optical disk technologies cannot store more than one terabyte of data, leading scientists to explore alternative technologies. Now, a team of Chinese researchers, led by Yuansheng Wang from the Chinese Academy of Sciences, has developed a three-dimensional ODS system that uses light-emitting nanocrystals (NCs) to store and retrieve information. Made from a transparent glass ceramic embedded with photostimulated luminescent rare-earth-doped metallic NCs, the new ODS system can store 3D optical data with increased capacity and improved security compared with current technologies.

High-security-level multi-dimensional optical storage medium: nanostructured glass embedded with LiGa 5 O 8 : Mn 2+ with photostimulated luminescence.

No‐Interference Reading for Optical Information Storage and Ultra‐Multiple Anti‐Counterfeiting Applications by Designing Targeted Recombination in Charge Carrier Trapping Phosphors

Junhe Zhou

Papers

No‐Interference Reading for Optical Information Storage and Ultra‐Multiple Anti‐Counterfeiting Applications by Designing Targeted Recombination in Charge Carrier Trapping Phosphors

The synthesis and photoluminescence of a single-phased white-emitting NaAlSiO4: Ce3+, Mn2+ phosphor for WLEDs

Thermally stable photoluminescence and long persistent luminescence of Ca3Ga4O9:Tb3+/Zn2+

Warm white light emitting from single composition SrGa12O19:Dy3+ phosphors for AC-LED

Insights into anti-thermal quenching of photoluminescence from SrCaGa4O8 based on defect state and application in temperature sensing