Ultra-broadband all-optical nonlinear activation function enabled by MoTe/optical waveguide integrated devices.

All-optical nonlinear activation functions (NAFs) are crucial for enabling rapid optical neural networks (ONNs). As linear matrix computation advances in integrated ONNs, on-chip all-optical NAFs face challenges such as limited integration, high latency, substantial power consumption, and a high activation threshold. In this work, we develop an integrated nonlinear optical activator based on the butt-coupling integration of two-dimensional (2D) MoTe and optical waveguides (OWGs).

Unlocking high photosensitivity direct laser writing and observing atomic clustering in glass.

The direct laser writing (DLW) of photoluminescent metal clusters is inspiring intensive research in functional glasses. However, understanding the influence of the host structure on cluster formation and visualizing DLW-induced clusters at the atomic scale remains challenging. In this work, we develop a highly photosensitive fluorophosphate glass through fluorine incorporation.

Precise mode control of laser-written waveguides for broadband, low-dispersion 3D integrated optics.

Three-dimensional (3D) glass chips are promising waveguide platforms for building hybrid 3D photonic circuits due to their 3D topological capabilities, large transparent windows, and low coupling dispersion. At present, the key challenge in scaling down a benchtop optical system to a glass chip is the lack of precise methods for controlling the mode field and optical coupling of 3D waveguide circuits. Here, we propose an overlap-controlled multi-scan (OCMS) method based on laser-direct lithography that allows customizing the refractive index profile of 3D waveguides with high spatial precision in a variety of glasses.

Localized Temperature Engineering Enables Writing of Heterostructures in Glass for Polarized Photoluminescence of Perovskites.

Metal halide perovskite (MHP) structures that exhibit polarized photoluminescence (PL) have attracted significant interest in fabricating light field regulation elements for display, imaging, and information storage applications. We report a three-dimensional direct lithography of heterostructures for controllable polarized PL inside glass by laser-induced localized temperature engineering. The heterostructures consisted of oriented periodic structures (OPSs) and MHP nanocrystals, and the mechanism for hierarchical distribution of heterostructures was illustrated.

Electronic State Engineering in Perovskite-Cerium-Composite Nanocrystals toward Enhanced Triplet Annihilation Upconversion.

Wavelength conversion based on hybrid inorganic-organic sensitized triplet-triplet annihilation upconversion (TTA-UC) is promising for applications such as photovoltaics, light-emitting-diodes, photocatalysis, additive manufacturing, and bioimaging. The efficiency of TTA-UC depends on the population of triplet excitons involved in triplet energy transfer (TET), the driving force in TET, and the coupling strength between the donor and acceptor. Consequently, achieving highly efficient TTA-UC necessitates the precise control of the electronic states of inorganic donors.

3D Imprinting of Voxel-Level Structural Colors in Lithium Niobate Crystal.

Advanced coloration methods are of pivotal importance in science, technology, and engineering. However, 3D structural colors that are critical for emerging multidimensional information representation and recording are rarely achievable. Here, a facile voxel-level programmable 3D structural coloration in the bulk lithium niobate (LiNbO ) crystal is reported.

Fabrication of Super-Sized Metal Inorganic-Organic Hybrid Glass with Supramolecular Network via Crystallization-Suppressing Approach.

Metal coordination compound (MCC) glasses [e.g., metal-organic framework (MOF) glass, coordination polymer glass, and metal inorganic-organic complex (MIOC) glass] are emerging members of the hybrid glass family.

Effectively writing low propagation and bend loss waveguides in the silica glass by using a femtosecond laser.

We report writing low-loss waveguides (WGs) by using a femtosecond laser in silica glass. A record low propagation loss of 0.07 dB/cm is achieved, and the lowest bend loss reaches 0.

Three-dimensional direct lithography of stable perovskite nanocrystals in glass.

Material composition engineering and device fabrication of perovskite nanocrystals (PNCs) in solution can introduce organic contamination and entail several synthetic, processing, and stabilization steps. We report three-dimensional (3D) direct lithography of PNCs with tunable composition and bandgap in glass. The halide ion distribution was controlled at the nanoscale with ultrafast laser-induced liquid nanophase separation.

Long-term optical information storage in glass with ultraviolet-light-preprocessing-induced enhancement of the signal-to-noise ratio.

This Letter describes the realization of long-term optical information storage in glass using an enhanced signal-to-noise ratio (SNR). We show that the photo-oxidation of ions in the glass matrix induced by ultraviolet light suppresses background signals, thereby enhancing by tenfold the SNR of ions photoluminescence (PL) of the dots written by a femtosecond (fs) laser. Thus, smaller dots exhibiting weak PL emission can be detected.

Self-organized phase-transition lithography for all-inorganic photonic textures.

Realizing general processing applicable to various materials by one basic tool has long been considered a distant dream. Fortunately, ultrafast laser-matter interaction has emerged as a highly universal platform with unprecedented optical phenomena and provided implementation paths for advanced manufacturing with novel functionalities. Here, we report the establishment of a three-dimensional (3D) focal-area interference field actively induced by a single ultrafast laser in transparent dielectrics.

Single-shot photon recording for three-dimensional memory with prospects of high capacity.

Femtosecond laser-induced modification in the glass has drawn considerable interest due to its widespread superiority in the applications of three-dimensional optical storage. In this Letter, we report that a single pulse could be used in optical memory with super-high writing speed. The photoluminescence image and spectrum indicate that one pulse-induced permanent photoreduction of to in -doped sodium aluminoborate glass can be achieved.

Fabricating low loss waveguides over a large depth in glass by temperature gradient assisted femtosecond laser writing.

We propose a strategy of temperature gradient assisted femtosecond laser writing for elaboration of low loss waveguides (WGs) over a large depth in glass. The matter flow driven by the temperature distribution is responsible for forming a highly densified WG core with tunable size. Importantly, the unique position of the guiding core outside the focus allows for abating the influence of laser energy redistribution and inscribing low loss deep WGs.

Polarization-sensitive and broadband germanium sulfide photodetectors with excellent high-temperature performance.

Layered materials, such as graphene, transition metal dichalcogenides and black phosphorene, have been established rapidly as intriguing building blocks for optoelectronic devices. Here, we introduce highly polarization sensitive, broadband, and high-temperature-operation photodetectors based on multilayer germanium sulfide (GeS). The GeS photodetector shows a high photoresponsivity of about 6.

Enhanced broadband excited upconversion luminescence in Ho-doped glasses by codoping with bismuth.

We report enhanced green and red upconversion (UC) luminescence in Ho3+-doped oxyfluoride germanate glass by introducing bismuth near-infrared active centers as sensitizers. The UC excitation bands at 750 and 970 nm show a full width at half-maximum of 20 and 45 nm, respectively. Energy transfer from sensitizers, the excited-state absorption, and phonon-coupled absorption of Ho3+ jointly contribute to the enhanced UC luminescence.

Lanthanide-doped NaGdF4 core-shell nanoparticles for non-contact self-referencing temperature sensors.

We report that non-contact self-referencing temperature sensors can be realized with the use of core-shell nanostructures. These lanthanide-based nanothermometers (NaGdF4:Yb(3+)/Tm(3+)@Tb(3+)/Eu(3+)) exhibit higher sensitivity in a wide range from 125 to 300 K based on two emissions of Tb(3+) at 545 nm and Eu(3+) at 615 nm under near-infrared laser excitation.

Regulation of structure rigidity for improvement of the thermal stability of near-infrared luminescence in Bi-doped borate glasses.

The effect of heat-treatment on the near-infrared (NIR) luminescence properties was studied in Bi-doped borate glasses. The luminescence intensity generally decreases with the increase of temperature, and the thermal stability can be improved by nearly 4.5 times with addition of 5 mol% La2O3.

Photoinduced luminescent carbon nanostructures with ultra-broadly tailored size ranges.

Carbon nanoparticles (CNPs), hollow CNPs, nanodiamonds, and hybrid graphene spheres (HGSPs) are produced by using fs laser ablation in solution. These carbon nanostructures emit tunable photoluminescence and two-photon luminescence. The photoinduced layer-by-layer assembly of graphene nanosheets is observed to form HGSPs with tailored broadly-ranged sizes for the first time.

Fabrication of silica nano/micro-fibers doped with one-dimensional assembly of silver nanoparticles.

Nano/micro fibers doped with metal nanocrystals are of great interest both theorectically and practically. Nevertheless, the ordered assembly of metal nanocrystals with desired patterns in nano/micro fibers still remains a big challenge, which constrains the further development of the performance of the material. In this investigation, we propose a facile strategy based on the sol-gel and coaxial electrospinning technique to fabricate silica submicron fibers incorporating ordered 1D array of silver nanoparticles.

Enhanced broadband near-infrared luminescence of Bi-doped oxyfluoride glasses.

Broadband near-infrared luminescence covering 900 to 1600 nm has been observed in Bi-doped oxyfluoride silicate glasses. The partial substitution of fluoride for oxide in Bi-doped silicate glasses leads to an increase of the intensity and lifetime of the near-infrared luminescence and blue-shift of the near-infrared emission peaks. Both Bi-doped silicate and oxyfluoride silicate glasses show visible luminescence with blue, green, orange and red emission bands when excited by ultra-violet light.

Comment on "Synthesis, functionalization and bioimaging applications of highly fluorescent carbon nanoparticles" by Sourov Chandra et al., Nanoscale, 2011, 3, 1533.

A recent paper in this journal reported the synthesis of highly fluorescent crystalline carbon nanoparticles by microwave irradiation of sucrose with phosphoric acid. The emission wavelengths reported in this investigation are always twice the corresponding excitation wavelengths and the full widths at half maximum are extremely small (15-20 nm). We suggest that their results and discussions are questionable.