Lasing in a femtosecond-laser-written single-scan waveguide fabricated in Tm-doped BGG glass.

We report lasing action in a femtosecond-laser-inscribed waveguide in thulium-doped barium-gallium-germanium oxide (BGG) glass. A laser cavity was assembled with this waveguide that provided a single-mode output of 62 mW when pumped at 1.6 µm.

Optimization of fs-laser-induced voxels in nonlinear materials via over-correction of spherical aberration.

In this Letter, over-correction of spherical aberration is used to counteract nonlinear effects such as Kerr self-focusing and plasma effects, resulting in more spherical and small-sized femtosecond laser-inscribed voxels within nonlinear materials. By strategically redirecting marginal focusing rays toward the beginning of the laser modification zone, the induced plasma prevents any rays from causing a structural modification beyond this zone, irrespective of any focus elongation caused by nonlinear effects. The method has been effectively validated across a range of materials, including ZnS, ZnSe, BIG, GeS, and SiO.

Tailoring ultrabroadband near-infrared luminescence in Bi-doped germanosilicate glasses.

Bi-doped glasses and optical fibers are extensively studied since they present broadband optical amplification in the near-infrared region (NIR), in which the optical telecommunication industry greatly depends for the transmission of optical signals. There are many scientific challenges about the NIR luminescent emissions from Bi ions, such as understanding its origin and further improving the associated optical amplification capacity. In this work, Bi-doped germanosilicate glass compositions with ultrabroadband NIR luminescence were fabricated, in the range of 925-1630 nm, which covers O, E, S, C, and L-telecommunication bands.

XRF online analyzer for measurements of PO content in phosphate slurry.

Online X-ray Fluorescence (XRF) setup was constructed and optimized for analysing the PO content in phosphate slurry (PS). Serval samples were analysed using two configurations of the setup, one with low and vertical flow and another with high and horizontal flow. The mean absolute error achieved through the first configuration was 0.

Effect of Photoinitiators Doped in PDMS for Femtosecond-Laser Writing: Characterization and Outcomes.

Herein, we have characterized in depth the effect of femtosecond (fs)-laser writing on various polydimethylsiloxane (PDMS)-based composites. The study combines systematic and nanoscale characterizations for the PDMS blends that include various photoinitiators (organic and inorganic agents) before and after fs-laser writing. The results exhibit that the photoinitiators can dictate the mechanical properties of the PDMS, in which Young's modulus of PDMS composites has higher elasticity.

Towards REPO nanocrystal-doped optical fibers for distributed sensing applications.

Rayleigh scattering enhanced nanoparticle-doped optical fibers, for distributed sensing applications, is a new technology that offers unique advantages to optical fiber community. However, the existing fabrication technology, based on in situ grown alkaline earth nanoparticles, is restricted to few compositions and exhibit a great dependence on many experimental conditions. Moreover, there is still several uncertainties about the effect of drawing process on the nanoparticle characteristics and its influence on the scattering enhancement and the induced optical loss.

Unveiling Structural Insights into Nanocrystal-Doped Optical Fibers via Confocal Raman Microscopy.

An in-depth characterization of nanoparticle-doped optical fibers is crucial to understand the potential new functionalities of the engineered glass and thus their applicability fields. The high temperatures of the manufacturing process strongly affect the nanoparticle features, and therefore, their analysis is necessary after fiber drawing. However, the difficulties associated with the use of atomic resolution microscopies to analyze the nanoparticle features in the fiber core, mainly related to sample preparation and expensive costs, usually prevent their study.

The role of tungsten oxide in Er-doped bismuth-germanate glasses for optical amplification in L-band.

A series of novel Er-doped bismuth-germanate glasses containing different tungsten concentrations with a molar composition of 97.5[(75 - x)GeO-25BiO-(x)WO]-2SbO-0.5ErO (x = 5, 10, 15, 20, and 25 mol%) were fabricated.

Demonstration of laser cooling in a novel all oxide GAYY silica glass.

We demonstrate laser induced cooling in ytterbium doped silica (SiO) glass with alumina, yttria co-doping (GAYY-Aluminum: Yttrium: Ytterbium Glass) fabricated using the modified chemical vapour deposition (MCVD) technique. A maximum temperature reduction by - 0.9 K from room temperature (296 K) at atmospheric pressure was achieved using only 6.

Toward low-loss mid-infrared GaO-BaO-GeO optical fibers.

The development of efficient and compact photonic systems in support of mid-infrared integrated optics is currently facing several challenges. To date, most mid-infrared glass-based devices are employing fluoride or chalcogenide glasses (FCGs). Although the commercialization of FCGs-based optical devices has rapidly grown during the last decade, their development is rather cumbersome due to either poor crystallization and hygroscopicity resilience or poor mechanical-thermal properties of the FCGs.

Near-infrared quantum cutting luminescence in Pr/Yb doped lead bismuth borate glass.

In this paper, thermally stable lead-bismuth-borate glasses were doped with 0.5 mol% of Pr ions at several concentration levels of Yb ions. Structural characterizations were performed via Raman, differential scanning calorimetry, optical absorption and fluorescence spectra.

The effect of particle size and water content on XRF measurements of phosphate slurry.

Phosphate slurries are studied using the XRF technique and the effect of the particle sizes and the water content parameters are analyzed and reported for the first time. Samples of the phosphate slurry with different particle sizes (425 µm, 300 µm, 250 µm, 200 µm, 160 µm and 106 µm) and different water contents (30%, 40%, 50%, 60%) were analyzed using an energy-dispersive X-ray spectrometer (EDXRF). The results show that the relative error of measurement varies with the particle size of the analyzed sample, the water content and the element measured.

Coaxial Mach-Zehnder Digital Strain Sensor Made from a Tapered Depressed Cladding Fiber.

An in-line digital optical sensor was proposed. It was built from a tapered depressed-cladding single-mode fiber and modeled as a coaxial Mach-Zehnder interferometer. The principle of operation of the optical digital sensor is based on the computation of the number of optical power transfer turning points (PTTP) from the transmission data of the component.

Nonlinear chalcogenide optical fiber couplers.

We demonstrate chalcogenide optical fiber couplers with a power-dependent coupling coefficient. The couplers are designed and fabricated using an AsSe fiber and characterized at a wavelength of 1938 nm, leading to a critical power of 126 W, the lowest ever reported for any optical fiber coupler. These nonlinear couplers enable all-optical switching and will be useful for passive mode-locking over a wide wavelength range from the telecommunication band to the mid-infrared.

Large area Bragg grating for pump recycling in cladding-pumped multicore erbium-doped fiber amplifiers.

We demonstrate for the first time that a Bragg grating can be written over a large area inside the cladding of a multicore erbium-doped fiber amplifier to increase the power conversion efficiency (PCE) by recycling the output pump power. Our results indicate that a Bragg grating covering ∼25% of the cladding area allows us to recycle 19% of the output pump power which leads to a relative increase of the PCE by 16% for an input pump power of 10.6 W in the specific case of an eight-core erbium-doped fiber with a length of 20.

Wearable Sensor Based on Flexible Sinusoidal Antenna for Strain Sensing Applications.

A flexible sinusoidal-shaped antenna sensor is introduced in this work, which is a modified half-wave dipole that can be used for strain sensing applications. The presented antenna is an improved extension of the previously introduced antenna sensor for respiration monitoring. The electrical and radiative characteristics of the sinusoidal antenna and the effects of the geometrical factors are studied.

Photosensitization agents for fs laser writing in PDMS.

This study aims at identifying compounds incorporated into Polydimethylsiloxane (PDMS) which produce large refractive index change under fs laser exposition, potentially leading to optimal writing of waveguides or photonic devices in such a soft host. Germanium derivative, titania and zirconite derivatives, benzophenone (Bp), irgacure-184/500/1173 and 2959 are investigated. We show a mapping of the RI index change relative to the writing speed (1 to 40 mm/s), the repetition rate (606 to 101 kHz) and the number of passes (1 to 8) from which we establish quantitative parameters to allow the comparison between samples.

Optimization & Characterization of Interdigitated Electrodes for Microbial Growth Monitoring.

This study optimally designed and implemented highly sensitive microscale interdigitated electrodes (IDEs) to monitor microorganisms' growth in diverse environments. Gold interdigitated electrodes (AuIDE) with 4 mm×4 mm effective sensing area and varying microscale interdigitate gaps were designed and fabricated. The electrodes were electrically characterized voltametrically.

Mid-infrared soliton self-frequency shift in chalcogenide glass.

Emerging applications in the mid-infrared (MIR) stimulate the growth and development of novel optical light sources. Soliton self-frequency shift (SSFS) in soft glass fiber currently shows great potential as an efficient approach toward the generation of broadly tunable femtosecond pulses in the MIR. In this work, we demonstrate a highly efficient tunable soliton source based on SSFS in chalcogenide glass.

Microscope-FTIR Spectrometry Based Sensor for Neurotransmitters Detection.

In this work, we present a new sensing approach for aqueous samples based on the microscope-FTIR spectrometer and applied for neurotransmitters. Our contribution in this work consists of a new sample handling system for the microscope-FTIR spectrometer based on a total reflective mirror, a heated hydrophobic layer for solvent removal/evaporation and sample confinement and a microfluidic system that handles sample injection unlike standard sample handling system which was based only on a total reflective mirror. In addition, another part of our contribution consists of proposing a new algorithm to extract molecular composition of the solution with high estimation ratios and based on the analysis of detected peaks on IR spectra.