Spectroscopy and Kerr-lens mode-locked operation of Yb:GdScO3 crystal.

A Kerr-lens mode-locked laser based on a Yb3+-doped disordered gadolinium scandate (Yb:GdScO3) crystal is reported for the first time, to the best of our knowledge. The crystal with the perovskite structure was grown using the Czochralski method, and its room temperature (RT) and low temperature (LT) spectra were also investigated. Due to the crystal's multisite structure (Gd3+/Sc3+ site), Yb:GdScO3 offers broad and intense polarized emission spectra in the near-infrared range (975-1075 nm). The stimulated emission cross section σSE is 0.46 × 10-20 cm2 at 1000 nm with an emission band width of 75.7 nm for E // b polarization. The continuous wave (CW) laser was operated pumped by a 976 nm fiber-coupled LD laser, resulting in a maximum output power of 8.74 W with a slope efficiency of 76.1% was obtained. Additionally, a pulses as short as 74 fs are generated at ∼1061.7 nm via Kerr-lens mode-locking. The average output power amounts to 32 mW at a pulse repetition rate of 101.4 MHz. All results indicate Yb:GdScO3 a promising candidate for 1 µm ultrashort laser.

Tunable and mode-locked Tm,Ho:GdScO3 laser.

A novel, to the best of our knowledge, Tm,Ho:GdScO3 crystal grown using the Czochralski method was investigated for its polarized spectroscopic properties and laser performance in both tunable continuous-wave (CW) and mode-locked regimes. The crystal's multisite structure (Gd3+/Sc3+ site) and Tm3+/Ho3+ dopants contributed to spectral broadening, enabling a tunable laser operation from 1914 to 2125 nm (with a broad range of 215 nm). Additionally, a pulse duration of 72 fs was achieved for E || b polarization. These results demonstrate the potential of the Tm,Ho:GdScO3 perovskite crystal as a promising gain material for ultrafast lasers operating around 2 µm.

Efficient continuous wave and broad tunable lasers with the Tm:GdScO3 crystal.

The spectroscopic properties and tunable laser performances of the orthorhombic perovskite Tm:GdScO3 crystal grown by the Czochralski method are comparatively studied for polarization along different crystallographic axes. The polarized emission spectrum of Tm:GdScO3 along the b-axis exhibits, to the best of our knowledge, the broadest bandwidth among all the single Tm3+-doped bulk gain media, indicating the strong inhomogeneous line broadening of Tm3+ ions in GdScO3 and thus leads to a broad and smooth gain spectrum. Tunable laser operation with a tuning range as broad as 321 nm from 1824 nm to 2145 nm is achieved, which indicates its potential for few-optical-cycle pulse generation in the 2-µm spectral range.

44-fs pulse generation at 2.05 µm from a SESAM mode-locked Tm:GdScO3 laser.

Pulses as short as 44 fs (6 optical cycles) with a spectral width of 120 nm are generated from a mode-locked solid-state laser near 2 µm employing an orthorhombic Tm:GdScO3 perovskite crystal. The average power amounts to 188 mW at a repetition rate of ∼77.6 MHz. The strong inhomogeneous line broadening in GdScO3 suggests optimum conditions for few-optical-cycle pulse generation of rare-earth ion doped GdScO3 bulk lasers.

Sensitive, simultaneous and quantitative detection of deoxynivalenol and fumonisin B1 in the water environment using lateral flow immunoassay integrated with smartphone.

Deoxynivalenol (DON) and fumonisin B1 (FB1), as a group of highly toxic secondary metabolites, have become a potential source of water environmental pollutants. To minimize two mycotoxins exposure to consumers, a dual lateral flow immunoassay (LFIA) integrated with the smartphone was reported for simultaneous and quantitative detection of DON and FB1 in the water environment. The significantly improved sensitivity was contributed to a smartphone-based device with the ability to image and analyze results. Under optimized conditions, the detection limits of DON and FB1 were calculated to be 3.46 and 2.65 ng/mL, which were approximately 25 and 10 folds lower than those of the visual detection of the LFIA. This method showed good specificity and a good dynamic linear detection for DON and FB1. The recoveries of DON and FB1 were evaluated by the spiked lake water, river water, and pond water, ranging from 92.47% to 106.2% with the relative standard deviation under 9.13%. Moreover, the results of the developed LFIA showed a high correlation with enzyme-linked immunosorbent assay (ELISA) results, with a correlation coefficient of 0.999 for DON and 0.996 for FB1, respectively. To sum up, the developed LFIA provides a promising platform for sensitive, simultaneous, quantitative, and on-site detection of DON and FB1 in the water environment.

Nep1-Like Proteins From the Biocontrol Agent Pythium oligandrum Enhance Plant Disease Resistance Independent of Cell Death and Reactive Oxygen Species.

Microbial necrosis and ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs) act as cytolytic toxins and immunogenic patterns in plants. Our previous work shows that cytolytic NLPs (i.e., PyolNLP5 and PyolNLP7) from the biocontrol agent Pythium oligandrum enhance plant resistance against Phytophthora pathogens by inducing the expression of plant defensins. However, the relevance between PyolNLP-induced necrosis and plant resistance activation is still unclear. Here, we find that the necrosis-inducing activity of PyolNLP5 requires amino acid residues D127 and E129 within the conserved "GHRHDLE" motif. However, PyolNLP5-mediated plant disease resistance is irrelevant to its necrosis-inducing activity and the accumulation of reactive oxygen species (ROS). Furthermore, we reveal the positive role of non-cytotoxic PyolNLPs in enhancing plant resistance against Phytophthora pathogens and the fugal pathogen Sclerotinia sclerotiorum. Similarly, non-cytotoxic PyolNLPs also activate plant defense in a cell death-independent manner and induce defensin expression. The functions of non-cytotoxic PyolNLP13/14 rely on their conserved nlp24-like peptide pattern. Synthetic Pyolnlp24s derived from both cytotoxic and non-cytotoxic PyolNLPs can induce plant defensin expression. Unlike classic nlp24, Pyolnlp24s lack the ability of inducing ROS burst in plants with the presence of Arabidopsis nlp24 receptor RLP23. Taken together, our work demonstrates that PyolNLPs enhance plant resistance in an RLP23-independent manner, which requires the conserved nlp24-like peptide pattern but is uncoupled with ROS burst and cell death.

Ho:LuAG single crystal fiber: growth, spectroscopy and laser characteristics.

Lutetium aluminum garnet single-crystal fiber (SCF, ∼ Φ 0.9 mm - 165 mm) doped with 0.5 at.% Ho3+ has been grown by the micro-pulling-down (µ-PD) technique. The room-temperature absorption and emission spectra exhibit similar features to the bulk crystal. Laser performances of the SCFs with two different pump configurations, i.e., pump guiding and free-space propagation, are studied by employing a 1.9-µm laser diode and a high-brightness fiber laser, respectively. Laser slope efficiencies obtained with both pump configurations can be higher than 50%, and a maximum output power of 6.01 W is achieved at ∼ 2.09 µm with the former pump. The comparable efficiency to the high-brightness pump is an indication of that high laser performance can also be expected through pump-guiding in the SCF even with a low pump beam quality.

Spatially Controlled Preparation of Layered Metallic-Semiconducting Metal Chalcogenide Heterostructures.

Spatially controlled preparation of heterostructures composed of layered materials is important in achieving interesting properties. Although vapor-phased deposition methods can prepare vertical and lateral heterostructures, liquid-phased methods, which can enable scalable production and further solution processes, have shown limited controllability. Herein, we demonstrate by using wet chemical methods that metallic Sn0.5Mo0.5S2 nanosheets can be deposited epitaxially on the edges of semiconducting SnS2 nanoplates to form SnS2/Sn0.5Mo0.5S2 lateral heterostructures or coated on both the edges and basal surfaces of SnS2 to give SnS2@Sn0.5Mo0.5S2 core@shell heterostructures. They also showed good light-to-heat conversion ability due to the metallic property of Sn0.5Mo0.5S2. In particular, the core@shell heterostructure showed a higher photothermal conversion efficiency than the lateral counterpart, largely due to its randomly oriented and polycrystalline Sn0.5Mo0.5S2 layers with larger interfacing area for multiple internal light scattering.

Wrapping Plasmonic Silver Nanoparticles inside One-Dimensional Nanoscrolls of Transition-Metal Dichalcogenides for Enhanced Photoresponse.

The low light absorption of transition-metal dichalcogenide (TMDC) nanosheets hinders their application as high-performance optoelectronic devices. Rolling them up into one-dimensional (1D) nanoscrolls and decorating them with plasmonic nanoparticles (NPs) are both effective strategies for enhancing their performance. When these two approaches are combined, in this work, the light-matter interaction in TMDC nanosheets is greatly improved by encapsulating silver nanoparticles (Ag NPs) in TMDC nanoscrolls. After the silver nitrate (AgNO3) solution was spin-coated on monolayer (1L) MoS2 and WS2 nanosheets grown by chemical vapor deposition, Ag NPs were homogeneously formed to obtain MoS2-Ag and WS2-Ag nanosheets due to the TMDC-assisted spontaneous reduction, and their size and density can be well controlled by tuning the concentration of the AgNO3 solution. By the simple placement of alkaline droplets on MoS2-Ag or WS2-Ag hybrid nanosheets, MoS2-Ag or WS2-Ag nanoscrolls with large sizes were obtained in large area. The obtained hybrid nanoscrolls exhibited up to 500 times increased photosensitivities compared with 1L MoS2 nanosheets, arising from the localized surface plasmon resonance effect of Ag NPs and the scrolled-nanosheet structure. Our work provides a reliable method for the facile and large-area preparation of NP/nanosheet hybrid nanoscrolls and demonstrates their great potential for high-performance optoelectronic devices.

Anion-dependent topochemical conversion of CoAl-LDH microplates to hierarchical superstructures of CoOOH nanoplates with controllable orientation.

Hierarchical superstructures of laterally or vertically oriented CoOOH nanoplates were prepared by topochemical conversion of CoAl-LDH microplates intercalated with CO32- or SO42- anions, respectively. The superstructure of vertically oriented nanoplates exhibited better electrocatalytic performance as compared to the lateral counterpart, attributable to the enlarged accessible surface area and promoted reaction kinetics.

High-performance Ho:YAG single-crystal fiber laser in-band pumped by a Tm-doped all-fiber laser.

We report on, to the best of our knowledge, the first Q-switched single-crystal fiber (Ho:YAG SCF) laser in the 2 µm spectral range, in-band pumped by a Tm-doped all-fiber laser. A continuous-wave laser with 12.5 W output power and Q-switched laser with 1.44 mJ pulse energy and 7.5 ns pulse duration at a repetition rate of 1 kHz were demonstrated. The high laser performance is attributed to the high gain, suppressed nonlinear effects, and easy thermal management which benefited from the unique geometric construction of the SCF.

Growth, spectral properties, and diode-pumped laser operation of a Nd3+-doped LaMgAl11O19 crystal.

A Nd3+-doped LaMgAl11O19 (Nd:LMA) crystal was grown by the Czochralski method. Room temperature polarized absorption spectra, fluorescence spectra, and fluorescence lifetime of the Nd:LMA crystal were measured and analyzed. The Judd-Ofelt parameters Ω2,4,6 were calculated to be 1.21×10-20, 3.63×10-20, and 2.35×10-20 cm2, respectively. The absorption and emission cross sections were calculated. Using a 790-nm diode laser as pump source, continuous-wave laser operation of an a-cut Nd:LMA crystal has been demonstrated with a maximum output power of 1.71 W and slope efficiency of 40.4% for a 1055 nm laser. Low-gain laser operation at 1082 nm is also realized with a maximum output power of 1.46 W and slope efficiency of 34.5%.