Ultrafast-Laser-Induced Tailoring of Crystal-in-Glass Waveguides by Precision Partial Remelting.

Space-selective laser-induced crystallization of glass enables direct femtosecond laser writing of crystal-in-glass channel waveguides having nearly single-crystal structure and consisting of functional phases with favorable nonlinear optical or electrooptical properties. They are regarded as promising components for novel integrated optical circuits. However, femtosecond-laser-written continuous crystalline tracks typically have an asymmetric and strongly elongated cross-section, which causes a multimode character of light guiding and substantial coupling losses.

Effect of Pulse Repetition Rate on Ultrafast Laser-Induced Modification of Sodium Germanate Glass.

We report an unexpected pulse repetition rate effect on ultrafast-laser modification of sodium germanate glass with the composition 22NaO 78GeO. While at a lower pulse repetition rate (~≤250 kHz), the inscription of nanogratings possessing form birefringence is observed under series of 10-10 pulses, a higher pulse repetition rate launches peripheral microcrystallization with precipitation of the NaGeO phase around the laser-exposed area due to the thermal effect of femtosecond pulses via cumulative heating. Depending on the pulse energy, the repetition rate ranges corresponding to nanograting formation and microcrystallization can overlap or be separated from each other.

One-Stage Femtosecond Laser-Assisted Deposition of Gold Micropatterns on Dielectric Substrate.

In this study, a simple one-stage laser-assisted metallization technique based on laser-induced backside wet etching and laser-induced chemical liquid-phase deposition is proposed. It allows for the fabrication of gold micropatterns inside the laser-written trace on a glass substrate. The reduction and deposition of gold inside and outside the laser-ablated channel were confirmed.

Defect-assisted photocatalytic activity of glass-embedded gallium oxide nanocrystals.

The use of glassceramics in photocatalysis is an attractive option for the realization of smart optical fibers and self-cleaning windows. Here we present the photocatalytic activity of germanosilicate glasses embedding GaO nanocrystals prepared by batch melting and glass heat treatment. The powdered material is used for UV-assisted degradation of rhodamine in water.

Hollow Channel Formation inside Sodium Aluminoborate Glass by Femtosecond Laser Writing and Distilled Water Etching.

Recently, the effect of nanograting formation was demonstrated for binary sodium borate glass with the possibility of data storage with an enhanced level of security. The obvious disadvantage of such glass is poor chemical stability, which limits real applications. In this paper, we show that the introduction of AlO allows preserving the possibility of nanograting formation with a significant increase of chemical resistance and thus to preserve optical memory applications.

Data on the femtosecond laser-induced formation of tracks in silver-containing zinc phosphate glass.

Direct femtosecond laser writing of tracks in the volume of silver-containing zinc phosphate glass is investigated. Tracks were written by the femtosecond laser irradiation with the wavelength of 1030 nm, the pulse duration of 180 fs and a scanning speed of 1 mm/s. The data shows the effect of the pulse repetition rate (10, 100 and 500 kHz) and the pulse energy (60-120 nJ) on the microstructure and optical properties of the laser-written tracks.

Glass: Home of the Periodic Table.

Glass is the most common material around us, and humankind uses it every day for more than 5000 years. However, from the chemical point of view, glass is the only material that could represent almost all elements of the Periodic Table inside itself, showing the effect of the Periodic Law on properties of the final material. In this paper, we show the most remarkable examples demonstrating that glass can rightfully be called "home" for all chemical elements providing different properties depending on its composition.

Multiwalled Carbon Nanotubes and the Electrocatalytic Activity of as the Basis of a Biosensor.

This paper considers the effect of multiwalled carbon nanotubes (MWCNTs) on the parameters of microbial biosensors. MWCNTs were shown not to affect the structural integrity of microbial cells and their respiratory activity. The positive results from using MWCNTs were due to a decrease in the impedance of the electrode.

Author Correction: Single shot laser writing with sub-nanosecond and nanosecond bursts of femtosecond pulses.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Multilevel data writing in nanoporous glass by a few femtosecond laser pulses.

Multidimensional data recording inside nanoporous high-silica glass by a femtosecond laser beam has been investigated. It is shown that three femtosecond laser pulses at pulse repetition rates up to 1 MHz are sufficient for recording 3 bits of information inside nanoporous glass, which is an order of magnitude lower than the number of pulses required for data writing in silica glass and provides a corresponding gain in the data writing speed. Multilayer data recording and reading were demonstrated providing the storage density corresponding to the capacity of 25 GB in the optical compact disc form factor.

Single shot laser writing with sub-nanosecond and nanosecond bursts of femtosecond pulses.

A method is proposed for efficient laser modification of fused silica and sapphire by means of a burst of femtosecond pulses having time separation in the range 10-3000 ps. Modification enhancement with the pulse separation increase in the burst was observed on the tens picoseconds scale. It is proposed that accumulated transient tensile strain in the excitation region plays a crucial role in modification by a sub-nanosecond burst.

Augmented excitation cross section of gadolinium ions in nanostructured glasses.

In this Letter, we present detailed absorption and emission data on nanostructured germanosilicate glasses and glass ceramics containing GaO nanophases and doped with Gd ions. The results show that these systems are suitable hosts for the enhancement of the excitation cross section of rare earth ions via energy transfer from the gallium oxide nanophase with a related quantum yield of 21%. The role of matrix composition and nanostructure morphology on the Gd emission is discussed.

Donor-Acceptor Control in Grown-in-Glass Gallium Oxide Nanocrystals by Crystallization-driven Heterovalent Doping.

Incorporation of doping ions in nanocrystals is a strategy for providing nanophases with functions directly related to ion features. At the nanoscale, however, doping can also activate more complex effects mediated by perturbation of the nanophase size and structure. Here, we report a paradigmatic case in which we modify grown-in-glass γ-Ga O nanophases by nickel or titanium doping of the starting glass, so as to control the concentration of oxygen and gallium vacancies responsible for the light emission.

Light-emitting Ga-oxide nanocrystals in glass: a new paradigm for low-cost and robust UV-to-visible solar-blind converters and UV emitters.

Wide-bandgap nanocrystals are an inexhaustible source of tuneable functions potentially addressing most of the demand for new light emitting systems. However, the implementation of nanocrystal properties in real devices is not straightforward if a robust and stable optical component is required as a final result. The achievement of efficient light emission from dense dispersions of Ga-oxide nanocrystals in UV-grade glass can be a breakthrough in this regard.

Spatially selective Au nanoparticle growth in laser-quality glass controlled by UV-induced phosphate-chain cross-linkage.

Herein we describe how UV excitation of localized electronic states in phosphate glasses can activate structural rearrangements that influence the kinetics of Au nanoparticle (NP) thermal growth in Au-doped glass. The results suggest a novel strategy to address the problem of controlling nano-assembly processes of metal NP patterns in fully inorganic and chemically stable hard materials, such as laser-quality glasses. We show that the mechanism is promoted by opening and subsequent cross-linkage of phosphate chains under UV excitation of non-bridging groups in the amorphous network of the glass, with a consequent modification of Au diffusion and metal NP growth.

Native amorphous nanoheterogeneity in gallium germanosilicates as a tool for driving Ga2O3 nanocrystal formation in glass for optical devices.

Nanoparticles in amorphous oxides are a powerful tool for embedding a wide range of functions in optical glasses, which are still the best solutions in several applications in the ever growing field of photonics. However, the control of the nanoparticle size inside the host material is often a challenging task, even more challenging when detrimental effects on light transmittance have to be avoided. Here we show how the process of phase separation and subsequent nanocrystallization of a Ga-oxide phase can be controlled in germanosilicates - prototypal systems in optical telecommunications - starting from a Ga-modified glass composition designed to favour uniform liquid-liquid phase separation in the melt.

A wind tunnel test of newly developed personal bioaerosol samplers.

In this study the performance of two newly developed personal bioaerosol samplers was evaluated. The two test samplers are cyclone-based personal samplers that incorporate a recirculating liquid film. The performance evaluations focused on the physical efficiencies that a personal bioaerosol sampler could provide, including aspiration, collection, and capture efficiencies.

Evaluation of physical sampling efficiency for cyclone-based personal bioaerosol samplers in moving air environments.

The need to determine occupational exposure to bioaerosols has notably increased in the past decade, especially for microbiology-related workplaces and laboratories. Recently, two new cyclone-based personal bioaerosol samplers were developed by the National Institute for Occupational Safety and Health (NIOSH) in the USA and the Research Center for Toxicology and Hygienic Regulation of Biopreparations (RCT & HRB) in Russia to monitor bioaerosol exposure in the workplace. Here, a series of wind tunnel experiments were carried out to evaluate the physical sampling performance of these two samplers in moving air conditions, which could provide information for personal biological monitoring in a moving air environment.

Microfluorescence analysis of nanostructuring inhomogeneity in optical fibers with embedded gallium oxide nanocrystals.

A spectroscopic protocol is proposed to implement confocal microfluorescence imaging to the analysis of microinhomogeneity in the nanocrystallization of the core of fibers belonging to a new kind of broadband fiber amplifier based on glass with embedded nanocrystals. Nanocrystallization, crucial for achieving an adequate light emission efficiency of transition metal ions in these materials, has to be as homogeneous as possible in the fiber to assure optical amplification. This requirement calls for a sensitive method for monitoring nanostructuring in oxide glasses.

Performance evaluation of two personal bioaerosol samplers.

In this study, the performance of two newly developed personal bioaerosol samplers for monitoring the level of environmental and occupational airborne microorganisms was evaluated. These new personal bioaerosol samplers were designed based on a swirling cyclone with recirculating liquid film. The performance evaluation included collection efficiency tests using inert aerosols, the bioaerosol survival test using viable airborne microorganism, and the evaluation of using non-aqueous collection liquid for long-period sampling.

Development of a personal bioaerosol sampler based on a conical cyclone with recirculating liquid film.

This article describes the development of a novel, high-performance personal aerosol sampler intended to monitor occupational air pollution, specifically, microbial constituents. This prototype sampler has a horizontally positioned conical cyclone with recirculating liquid film and an ejection supply of adsorptive liquid into the inlet nozzle. Airborne pollutants were collected in the adsorptive liquid, thus improving the survivability of microbiological aerosol samples.