We demonstrate the fabrication of straight and curved dual waveguides in $\text{GeO}_{2}-\text{PbO}$ glasses embedded with silver nanoparticles using femtosecond laser inscription. This research includes evaluating beam quality, propagation loss, and polarization of the double-wall waveguides.

This study is focused on the fabrication and characterization of various dual waveguides through femtosecond (fs) laser irradiation of GeO2-based glass samples. The objective of the present work is to develop diverse waveguide configurations, namely straight, S-bend and Y-shaped waveguides within GeO2–PbO glasses embedded with silver nanoparticles, utilizing a double-guide platform, for photonic applications such as resonant rings and beam splitters. Enhanced guidance was observed with a larger radius of curvature (80 mm) among the two distinct S-bend waveguides produced. The maximum relative propagation loss was recorded for the S-bend waveguide with a 40 mm radius, while the minimum loss was noted for the Y-shaped waveguide. In the latter configuration, with an opening angle of 5° and a separation of 300 µm between the two arms, an output power ratio of 50.5/49.5 between the left and right arms indicated promising potential for beam splitter applications. During the study, the quality factor (M2) of the proposed architectures was measured and the 80 mm S-bend configuration presented the best symmetry between the x and y axes; in the case of the Y configuration the similarity between the M2 values in both axes, for the first and second arms, indicates comparable light guidance.

This study focuses on the characterization of TeO2-ZnO samples prepared with different concentrations of rare-earth ions (Tm3+, Er3+, and Yb3+ ions) for potential appli-cations in photonics. Samples were produced with the melt-quenching technique and optical characterization, including luminescence and absorption measurements, was conducted, highlighting the influence of the rare-earth ion concentration on the emission intensities. The chromaticity diagram further illustrated the emitted colors, demonstrating light tuning ca-pabilities. The sample with a higher concentration of Er3+ and Yb3+ ions exhibited consistent green emission, making it suita-ble for LED and display applications. Green light emission was observed across all excitation power levels, with the high-est color purity achieved at the lowest excitation power of 14.4 W/cm2, whereas the one with a lower concentration of both rare - earth ions showed a broader range of emission colors, from blue to green, indicating superior light tuning and more versatile applications across the visible spectrum. Results of luminescence intensity as a function of different laser powers indicated that two photons participate in the emission of green and red light (550 and 660 nm) and three photons are associ-ated with the blue one (475 nm). The present results demon-strate a route to manage visible light emission and produce different photonic devices based on the efficiency frequency upconversion process of triply doped TeO2-ZnO glasses with different concentrations of rare-earth ions.

This study aims to produce and characterize different dual waveguides using femtosecond (fs) laser irradiation on GeO2-based glass samples. The work is motivated by previous results obtained with rare earth ions doped GeO2 - PbO glass, with and without silver nanoparticles, in which irradiation, with fs laser was successful. The work aims to manufacture different structures such as straight, curved, and Y waveguides (using the double guide configuration) for applications in photonics (resonant rings, beam splitters, among others) in GeO2 - PbO glasses with silver nanoparticles. For both, straight and S curved waveguides, better M-2 (beam quality factor) results were found for a distance between the guide walls of 10 mu m, when compared to 25 mu m. Moreover, among the two different curved guides produced it was also possible to observe better guidance when a larger radius of curvature (20 mm) was used; preliminary tests showed no guiding for 5 mm and 10 mm radius. The highest relative propagation loss was obtained for the S curved waveguide with a 25 mu m distance between the guide walls whereas the lowest one was found for the Y shaped waveguide; for this configuration (opening angle of 5 degrees and distance of 620 mu m between the two arms) an output power ratio between the left and right arm of 53.9/46.1 showed promising applications for beam splitters.

Investigation of the signal enhancement of Nd3+ codoped TeO2-ZnO pedestal waveguides, at 1064 nm, due to Au nanoparticles deposited over the core is presented for the first time. Nd3+ doped TeO2-ZnO thin film was obtained by RF Magnetron Sputtering deposition. The resulting core with 500 nm height and widths in the 4-40 mu m range, exhibited low roughness average in all area measured (0.48 +/- 0.04) nm. Minimum propagation losses of 2.2 dB/cm were observed for waveguide width of 40 mu m whereas an increase took place for smaller ones. Scanning electron microscopy (SEM) allowed the waveguide structure inspection and transmission electronic microscopy (TEM) the Au nanoparticles evaluation. The results showed that the Au nanoparticles contributed up to 75 % of relative gain enhancement, under 808 nm excitation. This increase was due to the local field growth in the proximity of the nanoparticles that enhances the density of excited Nd3+. The internal gain that considers the propagation losses reached positive values for larger core widths (above 8 mu m).

Dual waveguides were produced with ultrashort laser pulses in doped heavy metal glasses, showing low loss in straight and curved geometries, and demonstrating laser amplification when doped with rare earth ions.

This study focuses on the characterization of TeO 2 -ZnO samples prepared with different concentrations of rare-earth ions (Tm 3+ , Er 3+ , and Yb 3+ ions) for potential application in photonics. Samples were produced with the melt-quenching technique and optical characterization, including luminescence and absorption measurements, was conducted, highlighting the influence of the rare-earth ion concentration on the emission intensities. The chromaticity diagram further illustrated the emitted colors, demonstrating light tuning capabilities. The sample with a higher concentration of Er 3+ and Yb 3+ ions exhibited consistent green emission for LED and display applications green light is observed for all excitation powers (with the highest purity for the lowest excitation power (14.4 W/cm 2 ), whereas the one with a lower concentration of both rare - earth ions showed a broader range of emission colors, from blue to green, indicating superior light tuning and more versatile applications across the visible spectrum. Results of luminescence intensity as a function of different laser powers indicated that two photons participate in the emission of green light (545 and 650 nm) and three photons are associated with the blue one (477 nm). The present results demonstrate a route to manage visible light emission and produce different photonic devices based on the efficiency frequency upconversion process of triply doped TeO 2 -ZnO glasses with different concentrations of rare-earth ions.

We present the fabrication of dual waveguides in Ge2O-PbO glasses doped with silver nanoparticles using direct femtosecond laser inscription. The study involves results of beam quality, propagation loss, and polarization of the dual waveguides.

The paper explores the effects of Au nanoparticle (NP) islands deposited by sputtering technique on the surface of Nd3+-doped GeO2-PbO glasses, with double-line waveguides, produced via femtosecond laser processing for photonics. A Ti:sapphire femtosecond laser operating at 800 nm was employed to inscribe the waveguides directly into the glass, 0.7 mm beneath the surface. These waveguides were structured as pairs of parallel lines separated 10 μm. Additional procedures were undertaken to position the waveguides on the glass surface where Au NPs were deposited. Refractive index change of 10−3 at 632 nm was observed in both horizontal and vertical directions. Similar results for the beam quality factors (Mx2 and My2) at 632 nm and 1064 nm indicated x, y- symmetrical guiding. Photoluminescence and relative gain growth were observed due to Au NP islands. The relative gain reached 3.0 dB/cm representing an increase of approximately 450% when compared to samples without the Au NP islands, and was attributed to the local field growth in their vicinities. This study highlights the potential to change Nd3+-doped GeO2-PbO glasses optical properties with Au nanoparticle islands, opening up new and promising prospects for photonics and 1064 nm optical amplifiers.

This study introduces a novel method for producing Ag nanoclusters (NCs) within GeO2-PbO glasses doped with Tm3+ ions. Sample preparation involved the melt-quenching method, employing adequate heat treatment to facilitate Ag NC formation. Absorption spectroscopy confirmed trivalent rare-earth ion incorporation. Ag NC identification and the amorphous structure were observed using transmission electron microscopy. A tunable visible emission from blue to the yellow region was observed. The energy transfer mechanism from Ag NCs to Tm3+ ions was demonstrated by enhanced 800 nm emission under 380 and 400 nm excitations, mainly for samples with a higher concentration of Ag NCs; moreover, the long lifetime decrease of Ag NCs at 600 nm (excited at 380 and 400 nm) and the lifetime increase of Tm3+ ions at 800 nm (excitation of 405 nm) corroborated the energy transfer between those species. Therefore, we attribute this energy transfer mechanism to the decay processes from S1→T1 and T1→S0 levels of Ag NCs to the 3H4 level of Tm3+ ions serving as the primary path of energy transfer in this system. GeO2-PbO glasses demonstrated potential as materials to host Ag NCs with applications for photonics as solar cell coatings, wideband light sources, and continuous-wave tunable lasers in the visible spectrum, among others.

We report the physical, optical and nuclear radiation attenuation behaviours of tellurite-germanate (TeO2-GeO2-PbO) glasses reinforced with varying amounts of Eu2O3. The samples were synthesised using the conventional melt-quenching method and had the following composition (in wt.%): 33.34TeO2 - 33.33GeO2 33.33PbO (TGP). Different concentrations of Eu2O3 (in wt.%) were added to the glass composition, labelled TGP1, TGP2 and TGP3. The physical, optical and nuclear radiation attenuation properties were measured using both experimental and theoretical methods. At room temperature, the visible to near-infrared optical absorption spectrum ranged from 400 to 900 nm. The TGP1 sample with 1 wt% The Eu2O3 additive exhibited the lowest absorbance and the highest transparency. The TGP1 sample also exhibited the highest nuclear radiation absorption properties. The gamma-ray absorption capabilities of TGP1 were demonstrably superior to those of various types of glass shields and other old- and new-generation concrete-shielding materials. Thus, adding 1 wt % Eu2O3 to tellurite-germanate glasses would `improve nuclear radiation absorption and optical properties. It can also be concluded that expanded scientific community investigations in this area would be a significant step toward gaining a deeper understanding of these glass structures and determining what other optimisation tasks the addition of 1 wt% Eu2O3 can accomplish.

Random lasers have been studied using many materials, but only a couple have used glass matrices. Here, we present a study of zinc tellurite and aluminum oxide doped with different percentages of neodymium oxide (4 wt.%, 8 wt.%, and 16 wt.%) and demonstrate for the first time random laser action at 1337 nm. Laser emission was verified and the laser pulse's rise time and input-output power slope were obtained. A cavity composed of the sample's pump surface and an effective mirror formed by a second, parallel layer at the gain-loss boundary was probably the main lasing mechanism of this random laser system. The reason for the absence of emission at 1064 nm is thought to be a measured temperature rise in the samples' active volume.

Nd3+-doped GeO2-PbO glass with silver (Ag) nanoparticles (NPs) are produced with double line waveguides through fs laser processing for photonic applications. A Ti:sapphire fs laser at 800 nm was used to write the waveguides directly into the glass 0.7 mm beneath the surface. This platform is based on pairs of parallel lines with spacing of 10 µm, each pair being formed by two identical written lines but in two different configurations of 4 or 8 separately processed lines, which are coincident. The results of optical microscopy, absorbance measurements, refractive index change, beam quality factor (at 632 and 1064 nm), photoluminescence, propagation losses, and relative gain at 1064 nm are presented. The structural changes in the glass due to the presence of Ag NPs were investigated by Raman spectroscopy. At 632 and 1064 nm, x,y-symmetrical guiding was observed, and for both kinds of overlapping pulses, a refractive index alteration of 10−3 was found in both directions. Photoluminescence growth of ~47% at 1064 nm was observed due to the plasmonic effect of Ag NPs. In dual waveguides containing Ag NPs, the relative gain obtained increased by 40% and 30% for four and eight overlapping lines, respectively, at 600 mW of 808 nm pump power, when compared to waveguides without those metallic NPs. We highlight the resultant positive internal gains of 5.11 and 7.12 dB/cm that showed a growth of ~40% and ~30%, respectively, with respect to the samples without Ag NPs. The increase in photoluminescence and relative gain were related to the local field growth produced by Ag NPs. The present results show that the addition of Ag NPs impacts positively on the optical performance at 1064 nm of double line waveguides processed by fs laser writing in Nd3+-doped GeO2-PbO glass, opening news perspectives for photonics.

Random lasers are easier and cheaper to manufacture than regular ones, being made of several materials such as polymers, powders or dyes. Glass random lasers have been rarely studied due to their inhomogeneous broadened emission and low damage threshold. Here, we study Nd 3 +doped Te0 2 -ZnO-Al 2 0 3 glasses with different concentrations of rare-earth doping (4 wt.%, 8 wt.% and 16 wt.%). Emission intensity per pump fluence and fluorescence decay time measurements showed the potential of these glasses for random laser applications in the near-infrared region.

We report the production of double waveguides in Ge2O-PbO glasses doped with Nd3+ and silver nanoparticles by direct femtosecond laser writing. The beam quality measurements and refractive index change are presented.

The search for new materials to improve the efficiency of the light electricity conversion process of photovoltaic devices has grown in the last years. As there is always a mismatch between Si solar cell absorption and the solar spectrum, the use of luminescent materials as cover layer represents an alternative to overcome this problem. In this context the down and upconversion processes together with the plasmonic effects of metallic nanoparticles (NPs) to improve the luminescence of the materials play an important role. A review of recent works with glasses prepared with the melt quenching technique, used to increase the performance of photovoltaic devices due their luminescence is presented. So we present results of glasses based on GeO2 and TeO2 doped with rare-earth ions whose luminescence growth due to crystalline NPs (Ag or Au) or dielectric ones as TiO2, crystallized in anatase phase, increased the photovoltaic efficiency of up to 18%. Moreover, the influence of the rare-earth ions concentration on the efficiency increase in samples without NPs is also reviewed. The contribution of the transmittance of the material is highlighted as it also plays an important role to understand the enhancement of the Si solar cell performance.

A new double-line waveguide architecture produced in Nd3+ doped GeO2-PbO glasses is presented for photonic applications. The waveguides are written directly into Nd3+ doped GeO2-PbO glasses using a Ti:Sapphire femtosecond (fs) laser, operating at 800 nm, delivering 30 fs pulses at 10 kHz repetition rate and writing speed of 0.5 mm/s. Two parallel lines form a dual-waveguide each line being a result of either 4 or 8 superimposed lines. Results of propagation losses, M2 beam quality factor at 632 and 1064 nm, refractive index change, and relative gain at the signal wavelength (1064 nm) are presented. Structural changes, due to laser writing process were investigated by Raman spectroscopy. The observed near-field pattern image showed good waveguiding quality, consisting of a single, circular lobe. X,y-symmetrical guiding for both waveguides was observed. The relative gain reached 4.5 and 6.0 dB/cm for 4 and 8 superimposed lines, respectively, for 420 mW of 808 nm pumping. Propagation losses were 0.89 and 0.44 dB/cm, for 4 and 8 superimposed lines, respectively, leading to positive internal gain of 3.6 and 5.56 dB/cm. The results obtained in the present work demonstrate that this new double line architecture for Nd3+ doped GeO2-PbO glasses is promising for the fabrication of integrated amplifiers, lossless components and lasers.

We report the effect of TiO2 nanoparticles (NPs) on the optical properties of Er3+-doped and Er3+/Yb(3+-)codoped GeO2-PbO glasses. The present investigation demonstrates the adequate experimental procedure to produce TiO2 NPs in anatase structure (size distribution of TiO2 NPs centered at -50 nm) that favors the infrared-to-visible frequency upconversion (UC) process in Er3+-doped and Er3+/Yb3+ codoped GeO2-PbO. The samples were produced with the melt-quenching technique; phase transformation from amorphous phase to anatase crystalline structure takes place during the annealing that was performed at 420 ?. The feasibility of obtaining GeO2-PbO glasses with improved UC, due to Er(3+ )ions located in low symmetry sites promoted by the anatase structure of TiO2 NPs and the UC mechanisms from Yb3+ to Er3+ ions is presented. Photoluminescence growth of about 40% (at similar to 525 and 545 nm) was observed for the samples doped with Er3+ and TiO2 NPs in comparison with the one doped with Er3+ and without TiO(2 )NPs. Furthermore, an enhancement of-25% (525, 545 e 655 nm) was estimated for the UC intensity of samples codoped with Er3+/Yb3+ and with TiO2 NPs when compared with those without TiO2 NPs. The present investigation covers the lack of the literature related to the investigation of anatase structure of TiO2 NPs in Er3+-doped and Er3+/Yb3+ codoped GeO2-PbO glasses and can be extended to different hosts for different photonics applications.

In this study, three heavy metal oxide glasses (A:46.0PbO-42.0Bi(2)O(3)-12.0Ga(2)O(3), B:45.94PbO-42.66Bi(2)O(3)- 10.0Ga(2)O(3)-1.4BaO, C:72.8PbO-17.0GeO(2)-10.2Ga(2)O(3)) were synthesized to determine their optical and gamma-ray shielding properties in terms of assessing their potential applications in medical and industrial radiation facilities. Glasses were synthesized using melt quenching method. The optical band gap energy is calculated by the absorption spectrum measured at room temperature. We found a large band at 500 nm that refers to Bi + ions and appears to samples A and B that contain Bi2O3 in their compositions. Optical band gap energies were re -ported as 2.014 ev, 2.055 eV and 2.430 eV for A, B and C samples, respectively. Next, fundamental gamma-ray parameters were also determined using MCNPX general Monte Carlo code and Phy-X/PSD in 0.15-15 MeV photon energy. Our findings clearly showed that the B sample, which includes the highest concentration of Bi2O3, has a considerable advantage in terms of gamma-ray attenuation. Moreover, the results also showed that sample B has significantly higher attenuation properties than shielding concretes and several glass shields. It can be concluded that Bi2O3 is a useful component for heavy metal oxide glasses in terms of improving gamma-ray shielding capabilities for radiation shielding applications.