Search

Abstract Dynamic control of the optical properties of gold nanostructures is crucial for advancing photonics technologies spanning optical signal processing, on-chip light sources and optical computing. Despite recent advances in tunable plasmons in gold nanostructures, most studies are limited to the linear or static regime, leaving the dynamic manipulation of nonlinear optical properties unexplored. This study demonstrates the voltage-controlled Kerr nonlinear optical response of gold nanofilms via the electrothermal effect. By applying relatively low voltages (~10 V), the nonlinear absorption coefficient and refractive index are reduced by 40.4% and 33.1%, respectively, due to the increased damping coefficient of gold nanofilm. Furthermore, a voltage-controlled all-fiber gold nanofilm saturable absorber is fabricated and used in mode-locked fiber lasers, enabling reversible wavelength-tuning and operation regimes switching (e.g., mode-locking—Q-switched mode-locking). These findings advance the understanding of electrically controlled nonlinear optical responses in gold nanofilms and offer a flexible approach for controlling fiber laser operations.

We previously reported an ability of low-intensity vibration (LIV) to improve selected biomarkers of bone turnover and gene expression and reduce osteoclastogenesis but lacking of evident bone accrual. In this study, we demonstrate that a prolonged course of LIV that initiated at 2 weeks post-injury and continued for 8 weeks can protect against bone loss after SCI in rats. LIV stimulates bone formation and improves osteoblast differentiation potential of bone marrow stromal stem cells while inhibiting osteoclast differentiation potential of marrow hematopoietic progenitors to reduce bone resorption. We further demonstrate that the combination of LIV and RANKL antibody reduces SCI-related bone loss more than each intervention alone. Our findings that LIV is efficacious in maintaining sublesional bone mass suggests that such physical-based intervention approach would be a noninvasive, simple, inexpensive and practical intervention to treat bone loss after SCI. Because the combined administration of LIV and RANKL inhibition better preserved sublesional bone after SCI than either intervention alone, this work provides the impetus for the development of future clinical protocols based on the potential greater therapeutic efficacy of combining non-pharmacological (e.g., LIV) and pharmacological (e.g., RANKL inhibitor or other agents) approaches to treat osteoporosis after SCI or other conditions associated with severe immobilization.

ObjectiveTo investigate the factors that influence health literacy (HL) among Chinese patients with rheumatoid arthritis (RA) and furnish theoretical underpinnings for the development of intervention strategies aimed at enhancing patients’ quality of life.MethodsFrom May 2022 to December 2022, a comprehensive survey was conducted among both outpatients and inpatients diagnosed with (RA) in a tertiary hospital in China. The survey utilized various instruments, including a general information questionnaire, a chronic disease patient health literacy scale, the Health Assessment Questionnaire-Disability Index (HAQ-DI), the Chinese-translated Rheumatoid Arthritis Self-Efficacy Scale, the Chinese-translated Rheumatoid Arthritis Stigma Scale, and the Chinese-translated Compliance Questionnaire for Rheumatology Treatments.ResultsThe average scores of HL, self-efficacy, medication adherence, and disability index were 83.54 ± 17.43, 84.91 ± 14.37, 70.16 ± 11.24, and 0.26 ± 0.44, respectively. HL in Chinese RA patients was negatively correlated with age, erythrocyte sedimentation rate (ESR), number of tender joints, number of swollen joints, and disease activity, while positively correlated with self-efficacy and medication adherence. Age, disease activity, disability index, self-efficacy, and medication adherence are predictive factors of HL, and a predictive model has been initially constructed.ConclusionIn the management of RA, healthcare professionals should develop and implement effective intervention measures by focusing on improving medication adherence, enhancing patients’ self-efficacy, improving patients’ physical function, and reducing disease activity. This will help enhance the health literacy and promote clinical outcomes in RA patients.

Abstract An ideal blackbody absorbs all light impinging on it, and it radiates electromagnetic waves with a broad spectrum that depends only on the temperature. Conversely, a white object is characterized by a finite reflectance to visible light, hence being the opposite of a blackbody. Challenging this concept, here we find that various substances exhibit strong optical absorption capabilities like blackbodies when exposed to intense light, despite appearing pure white in the sunlight. We name this phenomenon photoinduced blackbody effect. Under near infrared light, the photoinduced blackbody effect is accompanied by photon avalanche optical frequency conversion and optical bistable luminescence. Namely, the energy states and absorption properties of the samples are modified under strong laser irradiation. The modified absorption transitions cause the switch of the sample from a quasi-whitebody into a quasi-blackbody via an avalanche mechanism. At the same time, the sample emits a broadband electromagnetic radiation, becoming a bright blackbody.

ABSTRACT Rapid and extensive sublesional bone loss after spinal cord injury (SCI) is a difficult medical problem that has been refractory to available interventions except the antiresorptive agent denosumab (DMAB). While DMAB has shown some efficacy in inhibiting bone loss, its concurrent inhibition of bone formation limits its use. Sialic acid‐binding immunoglobulin‐like lectin (Siglec)‐15 is expressed on the cell surface of mature osteoclasts. Anti‐Siglec‐15 antibody (Ab) has been shown to inhibit osteoclast maturation and bone resorption while maintaining osteoblast activity, which is distinct from current antiresorptive agents that inhibit the activity of both osteoclasts and osteoblasts. The goal of the present study is to test a Siglec‐15 Ab (NP159) as a new treatment option to prevent bone loss in an acute SCI model. To this end, 4‐month‐old male Wistar rats underwent complete spinal cord transection and were treated with either vehicle or NP159 at 20 mg/kg once every 2 weeks for 8 weeks. SCI results in significant decreases in bone mineral density (BMD, −18.7%), trabecular bone volume (−43.1%), trabecular connectivity (−59.7%), and bone stiffness (−76.3%) at the distal femur. Treatment with NP159 almost completely prevents the aforementioned deterioration of bone after SCI. Blood and histomorphometric analyses revealed that NP159 is able to greatly inhibit bone resorption while maintaining bone formation after acute SCI. In ex vivo cultures of bone marrow cells, NP159 reduces osteoclastogenesis while increasing osteoblastogenesis. In summary, treatment with NP159 almost fully prevents sublesional loss of BMD and metaphysis trabecular bone volume and preserves bone strength in a rat model of acute SCI. Because of its unique ability to reduce osteoclastogenesis and bone resorption while promoting osteoblastogenesis to maintain bone formation, Siglec‐15 Ab may hold greater promise as a therapeutic agent, compared with the exclusively antiresorptive or anabolic agents that are currently used, in mitigating the striking bone loss that occurs after SCI or other conditions associated with severe immobilization. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Pulsed lasers have wide applications in several fields, such as basic research, telecommunications, and industrial materials processing. A saturable absorber (SA) is a key component for pulse laser generation. However, the current SAs exhibit certain limitations. Hence, developing new nonlinear optical materials as SAs for pulse lasers generation is significantly important in ultrafast photonics and related applications. Metallic nanomaterials have attracted considerable attention because of their higher nonlinearity coefficients and wideband nonlinear response, which are induced by the surface plasmon resonance (SPR) effect. The SPR effect depends on the size and morphology of materials. Thus, the nonlinear optical absorption effect of gold nanomaterials for pulse laser generation must be explored. In this review, the optical properties of gold nanomaterials are introduced, including SPR absorption, photoluminescence properties, and surface‐enhanced Raman scattering effect. Then, the synthesis and characterization of different gold nanomaterials are reviewed. Subsequently, the nonlinear optical characteristics and devices based on gold nanomaterials are also introduced. Furthermore, the generation of different types of lasers using gold nanomaterial‐based devices is also reviewed. A comparison between gold nanomaterials and other SA materials is presented. Finally, the conclusion and outlook on gold nanomaterial‐based nonlinear optical devices are presented.

Recent years have witnessed growing research interest in dual-wavelength mode-locked fiber lasers for their pivotal role in diverse applications and the exploration of nonlinear dynamics. Despite notable progress in their development, achieving reliable mode-locked dual-wavelength operation typically necessitates intricate manual adjustments of the cavity’s polarization components. In this article, we present the realization of automatic mode-locking in a dual-wavelength soliton fiber laser. To provide guidance for the algorithm design, we systematically investigated the impact of polarization configurations and initial states on the laser’s operation through numerical simulations and linear scan experiments. The results indicate that operational regimes can be finely adjusted around the wave plate position supporting the mode-locked dual-wavelength solution. Furthermore, the laser exhibits multiple stable states at the mode-locked dual-wavelength point, with critical dependence on the initial conditions. Accordingly, we developed a two-stage genetic algorithm that was demonstrated to be effective for realizing automatic dual-wavelength mode-locking. To further improve the performance of the algorithm, a feedforward neural network was trained and integrated into the algorithm, enabling accurate identification of the dual-wavelength states. This study provides valuable insights into understanding how polarization configurations and initial conditions impact the operational regimes of dual-wavelength mode-locked fiber lasers. The algorithm developed can be extended to optimize other systems with multiple stable states supported at the same parameter point.

Perfluoroalkyl substances (PFAS) are persistent and pose a risk to human health. High throughput screening (HTS) cell-based bioassays may inform risk assessment of PFAS provided that quantitative in vitro to in vivo extrapolation (QIVIVE) can be developed. The QIVIVE ratio is the ratio of nominal (Cnom) or freely dissolved concentration (Cfree) in human blood to Cnom or Cfree in the bioassays. Considering that the concentrations of PFAS in human plasma and in vitro bioassays may vary by orders of magnitude, we tested the hypothesis that anionic PFAS bind to proteins concentration-dependently and therefore the binding differs substantially between human plasma and bioassays, which has an impact on QIVIVE. Solid phase microextraction (SPME) with C18-coated fibers served to quantify the Cfree of four anionic PFAS (perfluorobutanoate (PFBA), perfluorooctanoate (PFOA), perfluorohexane sulfonate (PFHxS) and perfluorooctane sulfonate (PFOS)) in the presence of proteins and lipid, medium components, cells and human plasma over five orders of magnitude in concentrations. The C18-SPME method was used to quantify the non-linear binding to proteins, human plasma and medium, and the partition constants to cells. These binding parameters were used to predict Cfree of PFAS in cell bioassays and human plasma by a concentration-dependent mass balance model (MBM). The approach was illustrated with a reporter gene assay indicating activation of the peroxisome proliferator-activated receptor gamma (PPARγ-GeneBLAzer). Blood plasma levels were collected from literature for occupational exposure and the general population. The QIVIVEnom ratios were higher than the QIVIVEfree ratios due to the strong affinity to proteins and large differences in protein contents between human blood and bioassays. For human health risk assessment, the QIVIVEfree ratios of many in vitro assays need to be combined to cover all health relevant endpoints. If Cfree cannot be measured, they can be estimated with the MBM and concentration-dependent distribution ratios.

Abstract Despite national and international efforts for the prevention of metabolic syndrome and its underlying diseases/disorders, its prevalence is still rising, especially in the middle-aged population. In this study, we explore the effect of high fat diet on the development of metabolic syndrome in middle-aged mice and to evaluate the potential benefits of voluntary physical exercise on the periphery as well as brain cognitive function, and to explore the potential mechanisms. We found that metabolic syndrome developed at middle age significantly impairs cognitive function and the impairment is associated with gene dysregulation in metabolic pathways that are largely affecting astrocytes in the brain. Eight-week voluntary wheel running at a frequency of three times a week, not only improves peripheral glucose control but also significantly improves learning and memory. The improvement of cognitive function is associated with restoration of gene expression involved in energy metabolism in the brain. Our study suggests that voluntary physical exercise is beneficial for metabolic syndrome-induced peripheral as well as cognitive dysfunction and can be recommended as therapeutic intervention for metabolic syndrome and associated diseases.

The administration of high-dose methylprednisolone (MP) for 24?48?h after traumatic spinal cord injury (SCI) has been shown to improve functional recovery. The known adverse effects of MP on skeletal muscle and the immune system, though, have raised clinically relevant safety concerns. However, the effect of MP administration on SCI-induced bone loss has not been evaluated to date. This study examined the adverse effects of high-dose MP administration on skeletal bone after acute SCI in rodents. Male rats underwent spinal cord transection at T3?T4, which was followed by an intravenous injection of MP and subsequent infusion of MP for 24?h. At 2 days, animals were euthanized and hindlimb bone samples were collected. MP significantly reduced bone mineral density (?6.7%) and induced deterioration of bone microstructure (trabecular bone volume/tissue volume, ?18.4%; trabecular number, ?19.4%) in the distal femur of SCI rats. MP significantly increased expression in the hindlimb bones of osteoclastic genes receptor activator of nuclear factor-?B ligand (RANKL; +402%), triiodothyronine receptor auxiliary protein (+32%), calcitonin receptor (+41%), and reduced osteoprotegerin/RANKL ratio (?72%) compared to those of SCI-vehicle animals. Collectively, 1 day of high-dose MP at a dose comparable to the dosing regimen prescribed to patients who qualify to receive this treatment approach with acute SCI increased loss of bone mass and integrity below the level of lesion than that of animals that had SCI alone, and was associated with further elevation in the expression of genes involved in pathways associated with osteoclastic bone resorption than that observed in SCI animals.

Polymer-based waveguide amplifiers are essential components in integrated optical systems, as their gain bandwidths directly determine the operating wavelength of optical circuits. However, development of the wideband gain media has been challenging, making it difficult to fabricate devices with broadband amplification capability. Rare earth ion-doped nanoparticles (NPs) are a key component in the gain media, and their full width at half maximum (FWHM) of the emission peak decides the final gain bandwidth of the gain media. Here, KMnF3: Yb, Er, Ce@KMnF3: Yb NPs with the broad full width at half maximum (FWHM) of the emission peak covering the S+C band was prepared. The NPs were synthesized using a hydrothermal method, and the FWHM of the emission peak of NPs reached 76 nm under the excitation of a 980 nm laser. The introduction of Ce3+ ions and a core-shell structure coating greatly enhanced the emission intensity of NPs at C band. Since KMnF3: Yb, Er, Ce@KMnF3: Yb NPs have exceptional broadband luminescence properties at C band, KMnF3: Yb, Er, Ce@KMnF3: Yb NPs can be the potential gain medium in the future polymer-based waveguide amplifiers.

Broadband and ultrafast response of plasmonic nanoparticles offer a significant advantage in optical modulation and allow ultrashort pulse generation from visible to mid‐infrared (MIR) region. However, many of the materials exhibit limited saturable absorption bandwidth in MIR spectral region, which limits the MIR pulses generation and the relative applications. Herein, it is shown that solution‐processed silver nanowires (AgNWs) exhibit an ultrabroadband localized surface plasmon resonance (LSPR) from 0.3 to over 25 μm, which contributes to wideband nonlinear optical response in the whole MIR region. Using those AgNWs as saturable absorbers (SA), all‐optical modulation in near infrared and MIR region is demonstrated. Mode‐locked lasers are realized at 1, 1.5, and 2 μm bands with minimal pulse duration down to a few hundreds of femtoseconds, and a Q‐switched laser at 3 μm band is achieved. The results show that AgNWs SA has the potential for constructing pulsed lasers in the MIR or even longer wavelength region.

Abstract Hexagonal phase (β) sodium rare earth tetrafluorides (NaREF4, RE = Y, Gd, Lu, et al.) are considered the ideal matrices for lanthanide (Ln) ions doped upconversion (UC) luminescence materials, because they can provide favorable crystal lattice structures for the doped luminescent Ln ions to make intensive emissions. However, the cubic phase (α) NaREF4 always preferentially forms at low reaction temperature in short time as it is dynamically stable. Therefore, it is hard to obtain small sized β-NaREF4 via the traditional solvothermal method. In this paper, small sized β-NaYF4:Yb,Er nanoparticles were synthesized by a heterogeneous-core-induced method via the solvothermal reaction. The heterogeneous α-NaGdF4/β-NaYF4: Yb, Er core–shell structure was confirmed by the local elemental mapping. The formation mechanism of β-NaYF4:Yb,Er shell on the surface of α-NaGdF4 core was explained in detail. We reasoned that a hetero interface with a lower lattice symmetric structure was produced by cation exchanges between the core and shell, which caused the preferential growth of anisotropic hexagonal phase shell. The existence of this hetero interface has also been proven by observation of Gd3+ UC emission.

We demonstrate tunable mid-infrared (MIR) Raman soliton generation in an all-solid fluorotellurite fiber pumped by a 1960 nm femtosecond fiber laser. All-solid fluorotellurite fibers are fabricated by using a rod-in-tube method. The core and cladding materials are TeO2-BaF2-Y2O3 (TBY) and AlF3-based glasses. Since the refractive index of AlF3-based glass is much lower than that of TBY glass, the zero-dispersion wavelength of all-solid fluorotellurite fiber can be tuned in a wide range by simply varying the core diameter of the fiber. By using a 0.5 m long all-solid fluorotellurite fiber with a core diameter of ∼ 2.7 μm as the nonlinear medium and a 1960 nm femtosecond fiber laser as the pump source, tunable MIR Raman soliton generation from 1.96 to 2.82 μm is obtained via soliton self-frequency shift by increasing the pump power. For the soliton laser source operating at 2.82 μm, the obtained optical-to-optical conversion efficiency is about 18% and the calculated pulse width is about 93 fs. Our results show that all-solid fluorotellurite fibers are promising nonlinear media for constructing tunable MIR ultrafast laser sources.

In this study, we prepared cubic-phase oleic-acid-coated KMnF3: Yb3+,Er3+ nanoparticles (NPs) and NaYF4:Yb3+,Er3+ NPs, which were about 23 nm. From the down-shifting emissions spectra of the two NPs obtained by 980 nm excitation, we observed the fact that the KMnF3: 18%Yb3+,1%Er3+ NPs were a luminescent material with a broadband near-infrared emission of 1.5 μm, and full-width at half-maximum (FWHM) of 55 cm−1, which was wider than that of the NaYF4: 18%Yb3+,1% NPs. Therefore, we believe that the oleic-acid-coated KMnF3:Yb3+,Er3+ NPs have great potential in fabricating broadband waveguide amplifiers. Through epitaxial growth of a KMnF3: Yb3+ active-shell on the core NPs, we compounded KMnF3:Yb3+,Er3+@KMnF3:Yb3+ core-active-shell NPs whose 1.5-μm infrared emissions intensity was 3.4 times as strong as that of the core NPs. In addition, we manufactured waveguide amplifiers using KMnF3:18%Yb3+,1%Er3+@KMnF3:2%Yb3+ NPs as the core materials of the waveguide amplifiers. When the input signal power was 0.2 mW and the pump power was 200 mW, we achieved a relative gain of 0.6 dB at 1534 nm in a 10-mm long waveguide.

Spinal cord injury (SCI) results in muscle atrophy, reduced force generation and an oxidative-to-glycolytic fiber type shift. The mechanisms responsible for these alterations remain incompletely understood. To gain new insights regarding mechanisms involved in deterioration of muscle after SCI, global expression profiles of miRs in paralyzed gastrocnemius muscle were compared between sham-operated (Sham) and spinal cord-transected (SCI) rats. Ingenuity Pathways Analysis of the altered miRs identified signaling via insulin, IGF-1, integrins and TGF-β as being significantly enriched for target genes. By qPCR, miRs 23a, 23b, 27b, 145, and 206, were downregulated in skeletal muscle 56 days after SCI. Using FISH, miR-145, a miR not previously implicated in the function of skeletal muscle, was found to be localized to skeletal muscle fibers. One predicted target of miR-145 was Cited2, a transcriptional regulator that modulates signaling through NF-κB, Smad3 and other transcription factors. The 3' UTR of Cited2 mRNA contained a highly conserved miR-145 seed sequence. Luciferase reporter assays confirmed that miR-145 interacts with this seed sequence. However, Cited2 protein levels were similar between Sham and SCI groups, indicating a biochemical interaction that was not involved in the context of adaptations after SCI. Taken together, the findings indicate dysregulation of several highly expressed miRs in skeletal muscle after SCI and suggest that reduced expression of miR-23a, 145 and 206 may have roles in alteration in skeletal muscle mass and insulin responsiveness in muscle paralyzed by upper motor neuron injuries.

Small fluoride nanoparticles (NPs) with strong down-conversion (DC) luminescence at 1.5 μm are quite desirable for optical fiber communication systems. Nevertheless, a problem exists regarding how to synthesize small fluoride NPs with strong DC emission at 1.5 μm. Herein, we propose an approach to improve 1.5 μm emission of BaLuF5:Yb3+,Er3+ NPs by way of combining doping Ce3+ ions and coating multiple BaLuF5: Yb3+ active-shells. We prepared the BaLuF5:18%Yb3+,2%Er3+,2%Ce3+ NPs through a high-boiling solvent method. The effect of Ce3+ concentration on the DC luminescence was systematically investigated in the BaLuF5:Yb3+,Er3+ NPs. Under a 980 nm laser excitation, the intensities of 1.53 μm emission of BaLuF5:18%Yb3+,2%Er3+,2%Ce3+ NPs was enhanced by 2.6 times comparing to that of BaLuF5:18%Yb3+,2%Er3+ NPs since the energy transfer between Er3+ and Ce3+ ions: Er3+:4I11/2 (Er3+) + 2F5/2 (Ce3+) → 4I13/2 (Er3+) + 2F7/2 (Ce3+). Then, we synthesized BaLuF5:18%Yb3+,2%Er3+,2%Ce3+@BaLuF5:5%Yb3+@BaLuF5:5%Yb3+ core-active-shell-active-shell NPs via a layer-by-layer strategy. After coating two BaLuF5:Yb3+ active-shell around BaLuF5:Yb3+,Er3+,Ce3+ NPs, the intensities of the 1.53 μm emission was enhanced by 44 times compared to that of BaLuF5:Yb3+,Er3+ core NPs, since the active-shells could be used to not only suppress surface quenching but also to transfer the pump light to the core region efficiently through Yb3+ ions inside the active-shells.

Alzheimer's disease (AD) is the most common cause of dementia among older people. At present, there is no cure for the disease and as of now there are no early diagnostic tests for AD. There is an urgency to develop a novel promising biomarker for early diagnosis of AD. Using surface-enhanced laser desorption ionization-mass spectrometry SELDI-(MS) proteomic technology, we identified and purified a novel 11.7-kDa metal- binding protein biomarker whose content is increased in the cerebrospinal fluid (CSF) and in the brain of AD dementia subjects as a function of clinical dementia. Following purification and protein-sequence analysis, we identified and classified this biomarker as S100A7, a protein known to be involved in immune responses. Using an adenoviral-S100A7 expression system, we continued to examine the potential role of S100A7 in AD amyloid neuropathology in in vitro model of AD. We found that the expression of exogenous S100A7 in primary cortico-hippocampal neuron cultures derived from Tg2576 transgenic embryos inhibits the generation of beta-amyloid (Abeta)(1-42) and Abeta(1-40) peptides, coincidental with a selective promotion of "non- amyloidogenic" alpha-secretase activity via promotion of ADAM (a disintegrin and metalloproteinase)-10. Finally, a selective expression of human S100A7 in the brain of transgenic mice results in significant promotion of alpha-secretase activity. Our study for the first time suggests that S100A7 may be a novel biomarker of AD dementia and supports the hypothesis that promotion of S100A7 expression in the brain may selectively promote alpha-secretase activity in the brain of AD precluding the generation of amyloidogenic peptides. If in the future we find that S1000A7 protein content in CSF is sensitive to drug intervention experimentally and eventually in the clinical setting, S100A7 might be developed as novel surrogate index (biomarker) of therapeutic efficacy in the characterization of novel drug agents for the treatment of AD.

In this work, cubic silver phosphate (Ag3PO4) nanoparticles (NPs) are prepared with the assistance of trisodium citrate. By controlling the reaction time, Ag3PO4 of different sizes were obtained. The possible growth mechanism of Ag3PO4 NPs based on trisodium citrate assistance is that trisodium citrate suppresses the deposition speed of Ag+ ions on the particle surface during the formation of Ag3PO4 NPs. The photocatalytic activity of the obtained Ag3PO4 NPs was verified based on the photodegradation of rhodamine B (RhB), methylene blue (MB) and methyl orange (MO), which showed that Ag3PO4 NPs had a high photocatalytic activity for MB in neutral solutions under visible-light illumination. A variety of methods, such as TEM, HRTEM, EDS, UV-vis, and FT-IR were used to investigate the characteristics of the typical Ag3PO4 NPs before and after the photodegradation experiments. The results indicated that the as-prepared Ag3PO4 NPs did not change much after the photodegradation test. Furthermore, the cyclic test confirmed its good stability, and the photocatalytic activity of Ag3PO4 NPs declined only by 4.4% after five recycles. This work provides a preparation strategy for Ag3PO4 NPs with a highly photocatalytic performance by an environmentally friendly method. [ABSTRACT FROM AUTHOR]

We report enhanced upconversion (UC) fluorescence in Tm3+ doped tellurite microstructured fibers (TDTMFs) fabricated by using a rod-in-tube method. Under the pumping of a 1560 nm femtosecond fiber laser, ultrabroadband supercontinuum light expanding from ~1050 to ~2700 nm was generated in a 4 cm long TDTMF. Simultaneously, intense 800 nm UC emission from the ³H4 → ³H6 transition of Tm3+ was observed in the same TDTMF. Compared to that pumped by a 1560 nm continuous wave fiber laser, the UC emission intensity was enhanced by ~4.1 times. The enhancement was due to the spectral broadening in the TDTMF under the pumping of the 1560 nm femtosecond fiber laser. [ABSTRACT FROM AUTHOR]

We report enhanced upconversion (UC) fluorescence in Tm3+doped tellurite microstructured fibers (TDTMFs) fabricated by using a rod-in-tube method. Under the pumping of a 1560 nm femtosecondfiber laser, ultrabroadband supercontinuum light expanding from ~1050 to ~2700 nm was generated in a 4 cm long TDTMF. Simultaneously, intense 800 nm UC emission from the ³H4 → ³H6 transition of Tm3+ was observed in the same TDTMF. Compared to that pumped by a 1560 nm continuous wave fiber laser, the UC emission intensity was enhanced by ~4.1 times. The enhancement was due to the spectral broadening in the TDTMF under the pumping of the 1560 nm femtosecondfiber laser. [ABSTRACT FROM AUTHOR]

In this work, the amorphous Eu3+-doped TiO2 spheres were synthesized by low cost mixed-solvent method, while the anatase and rutile spheres can be obtained by annealing the as-synthesized amorphous TiO2 spheres at elevated temperatures. The optical properties of Eu3+-doped TiO2 spheres were also investigated, and strong red emission (centered at 610 nm) with narrow line-width of 30 nm was observed under 465 nm or 394 nm excitations for the Eu3+-doped anatase TiO2 spheres. Our findings indicate the potential of using Eu3+-doped TiO2 spheres to achieve red emission with InGaN blue light emitting diodes (LEDs). Owing to the high light extraction efficiency in the GaN-based LEDs using anatase TiO2 spheres as demonstrated in our previous works, this work shows the strong potential of Eu3+-doped TiO2 spheres as the red phosphor material for high efficiency GaN-based white light-emitting diode. [ABSTRACT FROM AUTHOR]

Amorphous fluoride film was prepared by pulsed laser deposition and ultraviolet emissions were enhanced, The enhancement is attributed to a decrease of the Judd-Ofelt parameter omega2 induced by pulsed laser deposition, which precludes the transition rate from F2 to F4 and enhances the energy transfer process and populates the D2 level.

Yb(super 3+) and Er(super 3+) codoped amorphous Zn(sub 0.3)Al(sub 0.25)Pb(sub 0.3)Li(sub 0.09)Yb(sub 0.1)Er(sub 0.01)F(sub 2.37) (ZAPL) film is prepared by pulsed-laser deposition (PLD). The upconversion emission properties of the Yb(super 3+) and Er(super 3+) codoped ZAPL film is reported.

Small fluoride nanoparticles (NPs) with strong down-conversion (DC) luminescence at 1.5 μm are quite desirable for optical fiber communication systems. Nevertheless, a problem exists regarding how to synthesize small fluoride NPs with strong DC emission at 1.5 μm. Herein, we propose an approach to improve 1.5 μm emission of BaLuF5:Yb3+,Er3+ NPs by way of combining doping Ce3+ ions and coating multiple BaLuF5: Yb3+ active-shells. We prepared the BaLuF5:18%Yb3+,2%Er3+,2%Ce3+ NPs through a high-boiling solvent method. The effect of Ce3+ concentration on the DC luminescence was systematically investigated in the BaLuF5:Yb3+,Er3+ NPs. Under a 980 nm laser excitation, the intensities of 1.53 μm emission of BaLuF5:18%Yb3+,2%Er3+,2%Ce3+ NPs was enhanced by 2.6 times comparing to that of BaLuF5:18%Yb3+,2%Er3+ NPs since the energy transfer between Er3+ and Ce3+ ions: Er3+:4I11/2 (Er3+) + 2F5/2 (Ce3+) ! 4I13/2 (Er3+) + 2F7/2 (Ce3+). Then, we synthesized BaLuF5:18%Yb3+,2%Er3+,2%Ce3+@BaLuF5:5%Yb3+@BaLuF5:5%Yb3+ core-active-shell-active-shell NPs via a layer-by-layer strategy. After coating two BaLuF5:Yb3+ active-shell around BaLuF5:Yb3+,Er3+,Ce3+ NPs, the intensities of the 1.53 μm emission was enhanced by 44 times compared to that of BaLuF5:Yb3+,Er3+ core NPs, since the active-shells could be used to not only suppress surface quenching but also to transfer the pump light to the core region efficiently through Yb3+ ions inside the active-shells. [ABSTRACT FROM AUTHOR]

We present the design of fluorotellurite microstructured fibers (FTMFs) with near-zero-flattened dispersion profiles in the wavelength range of 1500-1600 nm for optical frequency comb (OFC) generation. The FTMFs are based on TeO2 -BaF2 - Y2O3 glass with a zero-dispersion wavelength of ~2160 nm. The fiber core is surrounded by the two layers of air holes. The addition of large size air holes in the outer layer is to shift the zero-dispersion wavelength of the fiber from ~2160 nm to the wavelength region of 1500-1600 nm. The addition of small size air holes in the inner layer is tomake the dispersion profile of the fiber become flat in the wavelength range of 1500-1600 nm. By optimizing the parameters (the core diameter, the air hole size, the pitch of air holes, etc.) of FTMFs, the fiber with the chromatic dispersion value between -0.5 and 0.3 ps/nm/km in thewavelength range of 1500-1600 nm is achieved. Furthermore, numerical simulations are used to showthe potential of the fiber for OFC generation via cascaded four-wave mixing. Flat topOFC extending from 1500 to 1600 nm with tunable mode spacing from 25 to 100 GHz can be generated in a 2-m-long fiber by using a 1550-nm laser with a pulse width of 0.85 ps and a peak power of 49 Was the pump source. The effects of stimulated Brillouin scattering on OFC generation are also investigated [ABSTRACT FROM AUTHOR]

Ho3+-doped fluoroindate glass fibers (FIGFs) based on InF3-GaF3-ZnF2-BaF2-SrF2-YF3-LiF-PbF2 glasses were fabricated by using a rod-in-tube method. By using a 92-cm-long Ho3+-doped FIGF as the gain medium and a 1120-nm fiber laser as the pump source, lasing at 2875 nm was obtained for a threshold pump power of 278 mW. By further increasing the pump power to 1224 mW, the obtained maximum output power was about 54.5 mW. The corresponding slope efficiency was about 6%. To the best of our knowledge, this is the first time to report lasing at 2875 nm from Ho3+-doped FIGFs. [ABSTRACT FROM AUTHOR]

We report the enhancement of phase-matched third harmonic generation (THG) via soliton self-frequency shift cancellation (SSFSC) in a fluorotellurite microstructured fiber (FTMF) pumped by a 1560 nm femtosecond fiber laser. The FTMF has two zero-dispersion wavelengths of 891 and 2012 nm for its slow axis. As the pump laser is polarized along the slow axis of the FTMF, phase matched THG at 629 nm is observed in the FTMF when the Raman soliton red-shifts to 1913 nm and the effective index at 1913 nm for the fundamental propagation mode matches with that at 629 nm for the high order propagation mode for a pump power of ~25.2 mW. Interestingly, the THG at 629 nm is enhanced very much when the Raman soliton meets the second zero-dispersion wavelength of the slow axis and further SSFSC occurs with increasing the pump power. Such an enhancement is due to the unchanged operating wavelength of the Raman soliton with an increase in the pump power when SSFSC occurs and the resulting increase in the interaction length between the Raman soliton and third harmonic. Our results show that high efficient THG with a designed wavelength can be obtained via SSFSC in dispersion engineered optical fibers. [ABSTRACT FROM AUTHOR]

All-solid fluorotellurite fibers are fabricated by using a rod-in-tube method. The core and cladding materials are TeO2-BaF2-Y2O3 (TBY) and AlF3-based glasses, respectively. Since the refractive index (~1.46) of AlF3-based glass is much lower than that (~1.84) of TBY glass, the zero-dispersion-wavelength of the fabricated fiber can be tuned from 2145 to 1507 nm by varying the fiber core diameter from 50 to 3 µm. By using a 0.6m long all-solid fluorotellurite fiber with a core diameter of ~7 µm as the nonlinear medium and a 2 µm femtosecond fiber laser as the pump source, 4.5W supercontinuum (SC) generation from 1017 to 3438 nm is obtained for a launched pump power of ~10.48 W. The corresponding optical-to-optical conversion efficiency is about 42.9%. In addition, no any damage of the fluorotellurite fiber is observed during the operation of the above SC light source. Our results show that all-solid fluorotellurite fibers are promising nonlinear media for constructing high power mid-infrared SC light sources. [ABSTRACT FROM AUTHOR]

Coherent supercontinuum light expanding from 1.4 to 4 lm is generated in a 4 cm long tapered fluorotellurite microstructured fiber (MF) pumped by a 1980 nm femtosecond fiber laser. The spectral broadening in the tapered fluorotellurite MF is caused by self-phase modulation, the Raman soliton, and red-shifted dispersive wave generation. Our results show that tapered fluorotellurite MFs are promising nonlinear medium for generating coherent broadband mid-infrared supercontinuum light. [ABSTRACT FROM AUTHOR]

Tunable mid-infrared dispersive waves are generated in a birefringent fluorotellurite microstructured fiber (FTMF) pumped by a 1560 nm femtosecond fiber laser. The FTMF have two zerodispersion wavelengths (ZDWs) for each polarization axis. The second ZDWs for the fast and slow axes of the FTMF are 2224 and 2042 nm, respectively. As the pump laser is polarized along the fast (or slow) axis of the FTMF, tunable mid-infrared dispersive waves from 2680 to 2725 nm (or from 2260 to 2400 nm) are generated in the FTMF when the Raman soliton meets the second zerodispersion wavelength of the fast (or slow) axis with increasing the pump power. Our results show that the designed FTMFs are promising nonlinear media for generating tunable mid-infrared light sources. [ABSTRACT FROM AUTHOR]

Flying particles with visible fluorescence were observed when a target, ZnF2:Tm3+/Yb3+, was irradiated by using a 953.6 nm pulsed infrared laser. Narrow blue beams showed the ejecting particles with upconversion emissions. The changing brightness along fluorescence traces exhibited the energy transfer from Yb3+ ions to Tm3+ ions and the depopulation of excited Tm3+ ions. Parameters of microexplosions induced by the pulsed laser were estimated by analyzing these flying particles. Compared with the target, these particles have strong infrared-to-ultraviolet upconversion ability. These results not only suggest a way to explore microexplosions induced by pulsed lasers but also provide a feasible scheme for developing ultraviolet upconversion materials. [ABSTRACT FROM AUTHOR]