Search Results (476)

Amplified Spontaneous Emission (ASE) sources are widely employed as highly stable broadband sources in fields such as high-precision navigation and optical detection. Erbium-doped fiber (EDF), as the core active component in ASE sources, has long been a key subject of thermal stability research. We fabricated a low-doped EDF with an 80 μm-cladding using the vapor phase doping (VPD) technique. This EDF was compared with a commercial 125 μm-cladding EDF using a double-pass forward (DPF) optical path configuration with a narrowband filter. We investigated the temperature-dependent characteristics of the ASE spectra generated by the two EDFs with different parameters. The temperature drift performance of the two EDFs was analyzed based on three critical indicators of the spectrum: mean wavelength, spectral bandwidth, and output power. In comparison with the commonly used EDF, the results show that a properly designed small-cladding EDF with an appropriate length can deliver higher ASE output power and exhibit a lower mean-wavelength temperature drift. This study provides an important guideline for promoting the miniaturization of high-precision fiber-optic sensing devices. Full article

Background/Objectives: Non-ablative vaginal Erbium-doped Yttrium Aluminium Garnet (Er:YAG) laser therapy has been proposed as a minimally invasive option for pelvic floor dysfunction (PFD), yet objective anatomical data using standardized measures remain limited. This study evaluated short-term anatomical and functional outcomes in a real-world care setting. Methods: This prospective single-arm interventional cohort study included women with PFD who underwent two sessions of non-ablative vaginal Er:YAG laser therapy. Outcomes were assessed at baseline, first follow-up (FU1), and second follow-up (FU2). Anatomical changes were measured using POP-Q parameters, including vaginal hiatus (Gh), total vaginal length (TVL), and compartmental staging. Sexual function was evaluated using the Female Sexual Function Index (FSFI). Pelvic floor muscle strength was assessed using the Oxford Scale. Non-parametric tests were used for repeated measures, and correlations between delivered laser energy and clinical outcomes were explored. Results: A total of 163 women were enrolled; 136 completed FU1 and 59 completed FU2. Median vaginal hiatus decreased significantly from baseline to FU1 and remained reduced at FU2 (p < 0.001). Improvements in anterior and posterior prolapse staging were observed, with a shift toward lower POP-Q stages at both follow-up visits. FSFI total scores did not change significantly across visits, although small changes were observed in specific domains, including a transient decrease in orgasms at FU1 (Δ = −0.2, p = 0.021) and a modest improvement in pain at FU2 (Δ = −0.4, p = 0.045). The magnitude of anatomical changes was modest, and their clinical relevance remains uncertain. Conclusions: Non-ablative vaginal Er:YAG laser therapy was associated with short-term improvements in vaginal hiatus and POP-Q prolapse staging in women with PFD, while sexual function remained stable. These findings provide objective anatomical data on early treatment effects in routine care, informing future evaluation of minimally invasive care models for pelvic floor dysfunction. Full article

Rare-earth elements (REEs), which include the entire lanthanide series together with scandium and yttrium, have unique electronic configurations and coordination chemical properties that provide them with special magnetic, optical, and redox abilities. Generally used for diagnostic imaging and theranostic applications, increasing evidence emphasizes their potential as direct anticancer agents. This review aims to present a thorough investigation of the studies published in the last ten years that focus on the intrinsic anticancer properties of REE-based molecular complexes and nanostructures, without discussing their recognized imaging functions. Rare-earth compounds exhibit selective cytotoxicity against malignant cells via mechanisms that mainly include modulations in the generation of reactive oxygen species, mitochondrial dysfunctions, interaction with DNA molecules, apoptosis, and ferroptosis induction, as well as radiosensitization. Molecular complexes that are based on the trivalent coordination chemistry of REEs enable them to target biomolecules like DNA and serum albumin. Nanostructured systems, on the other hand, render tumors more responsive to treatment by improving the cellular uptake, enabling surface functionalization, and controlling ROS generation. Terbium, thulium, yttrium, scandium, ytterbium, cerium, erbium, dysprosium, and europium show different levels of anticancer activity in both in vitro and in vivo cancer models. They often exert more toxicity in tumor cells than in normal tissues, thus exhibiting selective anticancer effects. The findings collectively underscore the therapeutic potential of REE-based compounds as novel metal-based anticancer agents and advocate for additional mechanistic and translational research to enhance their clinical applicability. Full article

This paper demonstrates a C-band continuously tunable mode-locked fiber laser based on a carbon nanotube saturable absorber (CNT-SA) and a commercial broadband tunable filter. The laser operates in the C-band with a continuous tuning range of 37.3 nm from 1532.6 nm to 1569.9 nm. The erbium-doped fiber (EDF) has a wide gain range, enabling the laser to achieve ultrafast mode-locking. Meanwhile, the tunable filter offers a broad wavelength selection range. This continuously tunable mode-locked fiber laser features a simple structure and a broad operating wavelength range, making it highly suitable for applications in optical communication, sensing, and laser processing. Full article

Improving the absorption of visible light in photocatalysts could enhance photocatalytic reactions and reduce energy consumption, particularly in sunny regions like Ecuador. This study reports the synthesis of ZnO and ZnO nanoparticles doped with 1.5 at.% Er, 5 at.% Al, and 1.5 at.% Er, 5 at.% Al using the sol–gel method. The effect of doping on the structure, morphology, absorption spectra, and photocatalytic properties was analyzed by XRD, SEM, EDS, and UV-Vis spectrophotometry. XRD confirmed the presence of the wurtzite ZnO structure, and UV-Vis diffuse reflection spectra showed a red shift in the band gap for doped ZnO compared to pristine ZnO. Photocatalytic activity was evaluated through the degradation of methyl orange (MO) under artificial visible light and natural sunlight in Quito, Ecuador. ZnO doped with Er/Al nanoparticles exhibited significantly enhanced photocatalytic performance under solar light, suggesting the potential for replacing artificial light and reducing operating costs in photocatalytic processes. Moreover, all doped samples retained the antibacterial properties of ZnO against B. subtilis, and Er/Al co-doping improved the inhibition of E. coli compared to undoped ZnO. Full article

Rare earth elements (REE), such as gadolinium (Gd) and erbium (Er), are increasingly recognised as emerging environmental contaminants due to their widespread use in industrial processes, electronics, and medical imaging applications. Despite their extensive presence in aquatic ecosystems, little is known about their developmental toxicity. In this study, Xenopus laevis embryos were exposed to environmentally relevant concentrations of Gd and Er during critical early developmental stages. The assessed endpoints included survival, malformations, growth (body length), and heart rate. Both Gd and Er caused significant sublethal effects, including increased axial malformations, reduced growth, and altered cardiac activity. To explore potential mechanisms of toxicity, the expression patterns of key developmental genes (fgf8, bmp4, sox9, egr2, rax1, pax6) and pro-inflammatory cytokines (tnfα, il1β, p65) were analysed using Real-Time PCR. The results showed dysregulation of gene expression, indicating disruption to pathways involved in morphogenesis and neurodevelopment. Elevated reactive oxygen species levels suggested that oxidative stress was a contributing factor. Raman spectroscopy confirmed biochemical changes affecting proteins, lipids, and nucleic acids, providing evidence of cellular stress and metabolic imbalance. Overall, our findings demonstrate that even low-level exposure to Gd and Er can impair amphibian embryonic development and disturb molecular homeostasis. These results emphasise the ecological risks of REE pollution and highlight the importance of ongoing environmental monitoring and long-term toxicological research. Full article

Background/Objectives: The purpose of this study was to investigate the laser removal of implant-supported ceramic single crowns, focusing on their efficiency and the potential reusability of the removed restorations. Methods: Sixty single crowns made of lithium disilicate were adhesively bonded to prefabricated titanium abutments in a total of six test series (n = 10). The test series were divided according to the different spacer settings of the crowns (90 µm, 120 µm, 150 µm) and the taper of the abutments (4°, 6°). After seven days of storage in distilled water, the single crowns were removed using an erbium-doped yttrium aluminium garnet (Er:YAG) laser. The number of laser pulses needed and the time required to remove the crowns were recorded. This was followed by a micro- and macroscopic score evaluation of the crowns using a fluorescent penetration method. Results: Laser removal of all sixty crowns was successfully performed. Using a taper of 6° and a spacer of 150 µm, the crowns were removed with significantly fewer pulses (61.40 (±36.78)). The taper and spacer had a significant effect on both the microscopic (p = 0.040) and macroscopic (p = 0.035) fracture patterns. Based on the final score of the fracture analysis, 44 of the 60 crowns could be classified as potentially reusable. The remaining 16 crowns failed due to purely macroscopic (7), purely microscopic (6), and combined microscopic and macroscopic (3) fracture behavior. Conclusions: Based on the results of this study, increasing the size of the taper and spacer has proven beneficial for laser removal in terms of time efficiency and non-destructive removal of crowns. Full article

Background: Low-level laser irradiation (LLLI) can promote wound healing. However, the biological effects of the erbium-doped yttrium aluminum garnet (Er:YAG) laser on gingival wound healing remain unclear. Objectives: To assess the effects of low-level Er:YAG laser irradiation on endothelial cell activity in vitro and on early phase gingival wound healing in vivo. Methods: In vitro, human umbilical vein endothelial cells were irradiated with a low-level Er:YAG laser (30 mJ/pulse, 10 Hz, 20 and 30 s, defocused, no water spray) and assessed for viability, cytotoxicity, and migration. Standardized bilateral wounds (4 × 1 mm) were created in the palatal gingiva of 14 male mice using a scalpel and curette. The wounds were irradiated for 20 s under the same irradiation settings, using a contact tip (diameter 800 μm) to induce superficial blood surface coagulation, while contralateral sites were assigned to controls in a split-mouth design. Postoperative wound area and mRNA expression of IL-6, TNF-α, VEGF, FGF-2, and TGF-β1 were analyzed after 48 h. Results: In vitro, LLLI significantly enhanced cell proliferation with/without increasing cytotoxicity. In the wound healing assay, the LLLI significantly promoted cell migration compared with the control. In vivo, the reduction in residual wound area in the laser group was comparable to that in the control group. IL-6 and TNF-α expressions were significantly downregulated, whereas VEGF was significantly upregulated in the laser group. Conclusions: Low-level Er:YAG laser irradiation enhances anti-inflammatory and pro-angiogenic effects, suggesting its potential in promoting gingival wound healing. Full article

Colloidal PbSe quantum dots are promising candidates as saturable absorbers for ultrafast fiber lasers, but their performance is often limited by surface-related defects and chemical instability, leading to aggregation under optical pumping. In this study, we present a freestanding PbSe/PbS quantum dot-polystyrene composite saturable absorber film, with PbS overcoating on PbSe to enhance surface passivation and oxidation resistance. The composite exhibits a saturation intensity of 5.76 kW·cm⁻², a modulation depth of 33%, and an optical damage threshold of 13.6 mJ·cm⁻². When integrated into a bidirectionally pumped erbium-doped fiber laser in the anomalous-dispersion regime, the device demonstrates self-starting soliton mode locking at an ultralow pump threshold of 6 mW, generating 1.06 ps pulses with a radio-frequency signal-to-noise ratio of approximately 65 dB. The spectra remain stable over an 8-month period, showing excellent environmental and operational durability. These findings confirm that PbSe/PbS quantum dots in a polymer matrix offer a robust, low-threshold saturable absorber platform for ultrafast fiber lasers. Full article

Erbium-165 (¹⁶⁵Er) is an Auger electron emitter with 7.2 electrons per decay and very few other emissions, making it an interesting candidate for Auger electron therapy. We present here a procedure for producing ¹⁶⁵Er by the ^natHo(p,n)¹⁶⁵Er nuclear reaction on a 16.5 MeV medical cyclotron. The target was prepared by pressing a Ho₂O₃:Al 1:1 (w/w) powder mixture on a Ag disc with a cylindrical depression in the center. With a 0.1 mm Nb foil in front, degrading the energy to 15 MeV, and water cooling at the back of the Ag disc, the target could withstand irradiation at currents up to 45 µA without showing any signs of damage. The beam tolerance of the target was also estimated by calculating the temperature and heat dissipation in the target via the numerical solution of the heat transport equations. For a 180 mg target, the production yield was 12.3 ± 1.9 MBq/µAh. The separation of two neighboring lanthanides is challenging, which led us to study the distribution coefficients for Er and Ho on commercially available LN2 resin for both HNO₃ and HCl eluents. Based on these values, we propose a purification procedure involving two successive LN2 columns for separating the ¹⁶⁵Er from Ho and Al, followed by a small TK221 column to concentrate the final eluate. No radionuclidic impurities were detected, and the chemical impurities found in the final formulation were traces of Ho, Er, Ca, Pb, and Fe. For three different chelators (DOTA, DTPA, and CHX-A″-DTPA), the effective molar activity of the final formulation was measured. The stability of the three complexes formed was also assessed upon incubation in mouse serum for 28 h. Full article

Rosacea is a chronic inflammatory skin disease characterized by erythematous, papular, and pustular lesions. Treatment for rosacea is tailored to the type and severity of lesions and the individual needs of the patient. The primary therapy involves topical and systemic treatments. Laser therapy is also an effective method. This review summarizes current knowledge on the application of pulsed dye lasers (PDLs), potassium titanyl phosphate (KTP) lasers, intense pulsed light (IPL), neodymium-doped yttrium aluminum garnet (Nd:YAG) lasers, carbon dioxide (CO₂) lasers, and erbium-doped yttrium aluminum garnet (Er:YAG) lasers in the treatment of rosacea. Research confirms that the PDL remains the gold standard, demonstrating excellent clinical efficacy. The KTP and IPL lasers provide comparable outcomes, with relatively fewer adverse effects. Due to its greater depth of penetration, the Nd:YAG laser is used to treat lesions in the deeper layers of the skin. In advanced forms of rosacea, such as rhinophyma, ablative lasers, including CO₂ and Er:YAG, are employed. This review summarizes the mechanisms of action, therapeutic applications, and adverse effects associated with the use of various laser types in the management of rosacea. Full article

This paper proposes a method to generate a low-noise 10.23 MHz time-frequency reference signal based on high-order harmonic locking of the repetition rate (f_r) of an optical frequency comb (OFC). An all-polarization-maintaining (PM) Erbium-doped fiber laser with a 122.76 MHz f_r is constructed using the nonlinear amplifying loop mirror (NALM) principle. By applying a feedback control to the intracavity piezoelectric actuator (PZT) and electro-optic modulator (EOM), the 10th harmonic of f_r is phase-locked to a high-performance rubidium atomic clock (Rb clock), achieving low-noise conversion from the Rb clock to the target signal. Experimental results show that the generated 10.23 MHz signal exhibits residual phase noise of −123.4 dBc/Hz at 1 Hz offset and −158 dBc/Hz at 1 MHz offset, and achieves a residual frequency stability of 3.52 × 10⁻¹³ @ 1 s and 3.65 × 10⁻¹⁵ @ 10,000 s. This harmonic locking scheme validates the advantages of photonic microwave generation in achieving ultra-low phase noise while preserving the long-term stability of atomic clocks, providing a strategic solution for next-generation BeiDou Navigation Satellite System (BDS) time-frequency payloads. Full article

This study develops a micro-ring resonator that provides optical amplification based on NaYF₄:5%Er³⁺ nanoparticles doped with SU-8. By utilizing the frequency selection properties of the micro-ring resonator, a filter with amplification capabilities is successfully developed. The device features a quality factor of 5.72 × 10⁴ and a free spectral range of 0.081 nm. Operating at an on-chip power of 108 mW, the micro-ring resonator amplifier exhibits a relative gain of 8.92 dB within a size of 2.3 cm × 1.5 cm. To the best of our knowledge, the amplification of optical signals in micro-ring resonators using erbium-doped polymers has not been reported. This technology highlights the significant potential of using erbium-doped materials to fabricate various integrated devices for on-chip optical amplification. Full article

Background: Traditional high-speed mechanical osteotomes cause substantial thermal and mechanical trauma, impairing bone healing. Erbium-doped yttrium-aluminum-garnet (Er:YAG) lasers, with water-mediated non-contact ablation, offer precise osteotomy potential with minimal collateral damage. This study demonstrated the feasibility of Er:YAG laser use for complex osteotomies and elucidated its multi-scale biological impacts on bone. Methods: A custom Er:YAG laser performed Z/arc-shaped osteotomies on fresh ovine bone (oscillating saw as control); paired rat tibial osteotomies; and compared laser vs. saw resection. Osteotomy surfaces were characterized by SEM/micro-CT; histological staining quantified thermal/mechanical damage. Bone marrow-derived mesenchymal stem cell (BMSC) adhesion, viability, and infiltration on cut surfaces were evaluated via LSCM. Result: In the ex vivo ovine model, the Er:YAG laser enabled precise execution of complex osteotomies (Z-shaped and arc-shaped), producing significantly narrower gaps than the oscillating saw (1.14 mm vs. 2.70 mm, p < 0.001) with high geometric fidelity and smooth surfaces free of burrs, micro-cracks, or debris. In the in vivo rat model, laser ablation simultaneously minimized both thermal and mechanical damage at the osteotomy interface: it reduced the thermal damage depth (154 vs. 592 µm, p < 0.001) and empty lacunae rate (16.8% vs. 41.8%, p < 0.001) while completely avoiding the mechanical damage zone (297 µm) induced by sawing. Furthermore, the laser-ablated surface established a highly bioactive interface, which significantly enhanced the adhesion (606 vs. 389 cells), viability (86.9% vs. 46.6%), and infiltration depth (196 vs. 75 µm) of bone marrow-derived mesenchymal stem cells (all p < 0.001). Conclusions: In conclusion, this proof-of-concept study demonstrates that the Er:YAG laser has the potential to enable precise bone resection while preserving microstructure. By establishing a pro-regenerative microenvironment, this technology shows promise as a biologically favorable alternative to conventional sawing, although further technical refinement and long-term validation are essential for its clinical translation. Full article

The management of dental caries has evolved from the traditional mechanical approach of “extension for prevention” to a biologically oriented philosophy centered on preserving natural tooth structures. Minimally invasive dentistry (MID) emphasizes early detection, risk assessment, prevention, and conservative intervention based on the lesion’s activity and depth. This review outlines current evidence on non-operative, micro-invasive, and minimally invasive strategies, including fluoride therapy, remineralizing agents such as casein phosphopeptide–amorphous calcium phosphate (CPP-ACP), self-assembling peptides that promote biomimetic enamel repair, sealants, and resin infiltration. Minimally invasive operative methods employ advanced technologies for selective tissue removal—chemomechanical systems (Carisolv, Papacarie, Brix3000), sono-and airabrasion, and new-generation polymeric and ceramic burs (SmartBur, Cerabur) designed to preserve sound dentin. Laser photoablation, particularly with erbium lasers (Er:YAG, Er,Cr:YSGG), enables precise cavity preparation with minimal thermal and mechanical stress. These approaches enhance patient comfort, reduce anesthesia requirements, and maintain tooth vitality. Despite limitations related to cost, equipment, and operator sensitivity, MID represents not only a set of refined clinical techniques but also a comprehensive, evidence-based treatment philosophy founded on biological principles, structural preservation, and the promotion of long-term oral health. Full article