Variation analysis of photonic lantern mode control ability under mode oscillation: a new approach.

In this Letter, we present a novel, to the best of our knowledge, image-based approach to analyze the mode control ability of a photonic lantern employed in diode laser beam combining, aiming to achieve a stable beam output. The proposed method is founded on theories of power flow and mode coupling and is validated through experiments. The findings demonstrate that the analysis of the beam combining process is highly reliable when the main mode component of the output light is the fundamental mode. Moreover, it is experimentally demonstrated that the mode control performance of the photonic lantern significantly influences the beam combining loss and the fundamental mode purity. In the essence of the variation-based analysis, a key advantage of the proposed method is its applicability even in the situation of a poor combined beam stability. The experiment only requires the collection of the far-field light images of the photonic lantern to characterize the model control ability, achieving an accuracy greater than 98%.

[Effect of LLLI on Secretion of ALP and Intracellular Calcium Concentration in Osteoblasts under Mechanical Stress].

In order to reveal the mechanism of LLLI accelerating teeth moving, we investigated the changes of alkaline phosphatase and intracellular calcium concentration when osteoblasts under stress were subjected low-level-laser-irradiation (LLLI). MG-63 cells were divided into four groups: control group, stress group, LLLI group and LLLI-stress group. Osteoblasts were subjected to the mechanical stress by a four-point bending system at 0.5 Hz and 3 000 µstrain. The secretions of ALP of each group are measured by spectrophotometer. In the second part, MG-63 cells were divided into two groups: stress group and LLLI-stress group. We checked intracellular calcium concentration via FCM and fluorescent indicator fluo-3/AM at 0, 5, 15, 30 and 60 min under stress. LLLI- stress group will receive LLLI for 1 min after stress. Compared to a control group, increased ALP secretions were observed in the other three groups. But ALP secretions in LLLI-stress group were lower than stress group and LLLI group. THE changing curve of intracellular calcium concentration in laser-stress groups is gentle instead of "jumping" in stress group. Proper stress, LLLI and combined application of these two can increase the secretions of ALP in osteoblasts compared to the control group. But the secretions of ALP decreased when combined application of stress and LLLI compared to using alone. LLLI can regulate the changing rhythm of concentration of the intracellular calcium to promote proliferation of MG-63 cell under stress, which means LLLI can reduce the bone-formation of osteoblasts under stress.

Photoluminescence properties and spectral structure analysis of NaLn(MoO4)2:Eu3+ (Ln = Gd, Y) phosphors.

In this paper, a facile synthetic route for the preparation of NaLn(MoO4)2:Eu3+ (Ln = Gd, Y) nanocrystals by a hydrothermal method is reported. The NaLn(MoO4)2:Eu3+ (Ln = Gd, Y) micro-powders were synthesized by a high temperature solid-state reaction. The optical properties of Eu3+ as a local structural probe are analyzed when being incorporated into NaLn(MoO4)2 (Ln = Gd, Y) micro-powders and nanocrystals. In NaLn(MoO4)2:Eu3+ (Ln = Gd, Y), the substitution of Ln3+ by Eu3+ is confirmed and the point symmetry of the site and crystal structure are analyzed. The luminescence mechanism and the size dependence of their fluorescence properties in NaLn(MoO4)2:Eu3+ (Ln = Gd, Y) micro-powders and nanocrystals are also discussed in detail.

Orthogonally polarized dual-wavelength Nd:YAlO(3) laser at 1341 and 1339 nm and sum-frequency mixing for an emission at 670 nm.

We report a diode-pumped continuous wave (cw) orthogonally polarized dual-wavelength laser at 1339 and 1341 nm with a single b-cut Nd:YAlO(3) (Nd:YAP) crystal. By adjusting the tilt angle of the uncoated glass plate inserted in the laser cavity, we can control the cavity losses of two polarized directions. The output wavelengths are 1339 nm in a-axis polarization and 1341 nm in c-axis polarization, respectively, which are orthogonal to each other. At an incident pump power of 17.3 W, the cw output power obtained at 1339 and 1341 nm is 1.6 and 2.3 W, respectively. Furthermore, intracavity sum-frequency mixing at 1339 and 1341 nm was then realized in a KTiOPO(4) (KTP) crystal to reach the red range. To our knowledge, this is the first work realizing an orthogonally polarized dual-wavelength Nd:YAP laser based on the (4)F(3/2-)-(4)I(13/2) transition. Such a dual-wavelength laser would be especially valuable as a compact laser source to generate terahertz emission because the frequency difference between 1339 and 1341 nm is about 0.9 THz.

CW 50W/M2 = 10.9 diode laser source by spectral beam combining based on a transmission grating.

An external cavity structure based on the -1st transmission grating is introduced to spectral beam combining a 970 nm diode laser bar. A CW output power of 50.8 W, an electro-optical conversion efficiency of 45%, a spectral beam combining efficiency of 90.2% and a holistic M(2) value of 10.9 are achieved. This shows a way for a diode laser source with several KW power and diffraction-limited beam quality at the same time.

3D-Printed Bioactive Scaffold Loaded with GW9508 Promotes Critical-Size Bone Defect Repair by Regulating Intracellular Metabolism.

The process of bone regeneration is complicated, and it is still a major clinical challenge to regenerate critical-size bone defects caused by severe trauma, infection, and tumor resection. Intracellular metabolism has been found to play an important role in the cell fate decision of skeletal progenitor cells. GW9508, a potent agonist of the free fatty acid receptors GPR40 and GPR120, appears to have a dual effect of inhibiting osteoclastogenesis and promoting osteogenesis by regulating intracellular metabolism. Hence, in this study, GW9508 was loaded on a scaffold based on biomimetic construction principles to facilitate the bone regeneration process. Through 3D printing and ion crosslinking, hybrid inorganic-organic implantation scaffolds were obtained after integrating 3D-printed ß-TCP/CaSiO3 scaffolds with a Col/Alg/HA hydrogel. The 3D-printed ß-TCP/CaSiO3 scaffolds had an interconnected porous structure that simulated the porous structure and mineral microenvironment of bone, and the hydrogel network shared similar physicochemical properties with the extracellular matrix. The final osteogenic complex was obtained after GW9508 was loaded into the hybrid inorganic-organic scaffold. To investigate the biological effects of the obtained osteogenic complex, in vitro studies and a rat cranial critical-size bone defect model were utilized. Metabolomics analysis was conducted to explore the preliminary mechanism. The results showed that 50 µM GW9508 facilitated osteogenic differentiation by upregulating osteogenic genes, including Alp, Runx2, Osterix, and Spp1 in vitro. The GW9508-loaded osteogenic complex enhanced osteogenic protein secretion and facilitated new bone formation in vivo. Finally, the results from metabolomics analysis suggested that GW9508 promoted stem cell differentiation and bone formation through multiple intracellular metabolism pathways, including purine and pyrimidine metabolism, amino acid metabolism, glutathione metabolism, and taurine and hypotaurine metabolism. This study provides a new approach to address the challenge of critical-size bone defects.

Quasi-three-level neodymium-doped yttrium aluminum garnet laser emitting at 885 nm.

We present a diode-pumped quasi-three-level neodymium-doped yttrium aluminum garnet (Nd:YAG) laser at 885 nm, based on the 4F3/2-4I9/2 transition, generally used for a 946 nm emission. Combined with polarization components (Nd:YAG), the electro-optical crystal KH2PO4 (KDP) formed a Lyot filter in the cavity and compressed the available gain bandwidth. With an incident pump power of 9.2 W, a 714 mW continuous-wave (CW) output at 885 nm was achieved, and the optical-to-optical efficiency was 7.8%. With an adjustable voltage applied to the KDP crystal, the laser wavelength could be tuned from 885 nm to 884 nm. A simultaneous dual-wavelength Nd:YAG laser at 885 nm and 884 nm was also realized by adjusting the free spectral range of the Lyot filter. To our knowledge, it is the first study that has realized the tuning between the 884 and 885 nm lines and the simultaneous dual-wavelength CW laser operation at 885 nm and 884 nm.

Optically Pumped Monolayer MoSe2 Excitonic Lasers from Whispering Gallery Mode Microcavities.

Developing integrable, nanoscale, and low-energy-consumption lasers is a crucial step toward on-chip optical communications and computing technologies. The strong exciton-photon interaction that emerged in monolayer transition metal dichalcogenides (TMDs) holds promise for engineering and integration. Herein, we prepare the MoSe2/microsphere cavities excitonic lasers by placing SiO2 microspheres on top of a monolayer MoSe2 film. By virtue of continuous-wave exciting MoSe2/microsphere whispering gallery mode (WGM) cavities, we realize multiple excitonic WGM lasing in the emission wavelength range of ∼750-875 nm at room temperature with tunable properties of free spectral range (FSR) and full width at half-maximum (fwhm) by varying the microsphere size. Theoretical calculations based on the finite element method (FEM) using COMSOL software were utilized to identify lasing modes and reveal the corresponding electric field distribution. These findings help to deepen fundamental understanding of excitonic WGM lasing and provide a promising research platform for integrable, scalable, and low-cost laser devices.

Facile template free synthesis of KLa(MoO4)2:Eu3+,Tb3+ microspheres and their multicolor tunable luminescence.

Trivalent rare-earth (RE(3+) = Eu(3+), Tb(3+)) ion activated KLa(MoO4)2 microspheres have been synthesized at 180 °C via a facile hydrothermal route without using any templates, surfactant, or other organic additives. X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), photoluminescence (PL), and photoluminescent excitation spectra (PLE) were employed to characterize the samples. It is found that the pH value in the initial solution is responsible for crystal phase, shape determination and emission intensity of final products. The possible formation mechanism for products with uniform spheres has been presented. Furthermore, a systematic study on the photoluminescence of RE(3+) (RE(3+) = Eu(3+), Tb(3+)) doped KLa(MoO4)2 samples has been explored in order to obtain the multicolor tunable emission by varying the Tb(3+)/Eu(3+) ratio. The tunable luminescence may be potentially applied in fields such as solid state lighting and field emission displays.

Hydrothermal synthesis, electronic structure and tunable luminescence of single-phase Ca5(PO4)3F:Tb3+,Eu3+ microrods.

Uniform and well-crystallized calcium fluorapatite [Ca5(PO4)3F, FAP] microrods have been successfully synthesized by a facile one-step hydrothermal synthesis method using sodium citrate as the crystal modifier. X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), photoluminescent excitation spectra (PLE) and decay studies were employed to characterize the samples. The electronic structure and orbital population of FAP were also determined by means of density functional theory calculations. Under ultraviolet irradiation, the FAP:Tb(3+),Eu(3+) samples exhibit a blue-light emission of the host matrix, as well as the typical green emission band of the Tb(3+) ions, and a red-light emission of Eu(3+). The highly intense red emission bands of the Eu(3+) ions were attributed to the effective energy transfer from the Tb(3+) to Eu(3+) ions, which has been justified through the luminescence spectra and the fluorescence decay dynamics. The luminescence colors of FAP:Tb(3+),Eu(3+) microrods can be easily tuned by changing the concentration of Eu(3+) ions. The results reveal that the combination of the self-activated luminescence and rare earth-doping emission in FAP:Tb(3+),Eu(3+) microrods could result in tunable emission in a large color gamut, which can be used as a potential candidate for white-light-emitting diodes and other display devices.