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We report an efficient high-power Yb:YCa4O(BO3)3 laser that was passively Q-switched by a few-layer WS2 saturable absorber. A maximum average output power of 4.05 W was produced at a pulse repetition rate of 606 kHz, with an optical-to-optical efficiency of 40.5% and a slope efficiency of 47%. The resulting pulse energy, duration, and peak power were 6.67 μJ, 66 ns, and 101 W, respectively. Our work demonstrates the great potential of few-layer WS2 and other 2D transition metal dichalcogenides as saturable absorbers for developing high-power, high-repetition-rate, nanosecond, pulsed solid-state lasers.

Highly efficient high-power laser operation around 1084 nm is demonstrated of the Yb 0 . 14 : Y 0 . 77 Gd 0 . 09 Ca 4 O ( BO 3 ) 3 mixed crystal in a compact plano-concave resonator, producing an output power of 18.1 W in free-running mode, with optical-to-optical and slope efficiencies being, respectively, 60% and 70% with respect to incident pump power. In laser action achieved with the high-gain short-wavelength oscillation being suppressed, the highest output power reaches 16.2 W with an optical-to-optical efficiency of 50.3%, while the slope efficiency amounts to 58%. The results presented reveal the superiority of the Yb-ion doped mixed oxyborate crystal to the existing Yb-ion or Nd-ion crystals capable of generating high-power laser radiation around 1084 nm.

Repetitively Q-switched operation was achieved with a Yb:YCa 4 O(BO 3 ) 3 laser in a wide repetition rate range from 20 down to 0.1 kHz. An output power of 6.81 W at 20 kHz was generated with pulse duration of 42 ns; while operated at a low repetition rate of 0.1 kHz, the laser produced 0.53 W of output power with pulse width of 21 ns, the resulting pulse energy and peak power amounted respectively to 5.3 mJ and 252.4 kW.

Phytochelatin synthase (PCS) plays an essential role in heavy metal detoxification in plants and fungi, via the catalyzation of phytochelatins (PCs) biosynthesis from the substrate of glutathione (GSH). Two PCS genes AtPCS1 and AtPCS2 are present in Arabidopsis genome. However, loss of function of only the AtPCS1 gene resulted in undetectable PCs and the consequent metal hypersensitivity in the corresponding mutant cad1 - 3 ,while in vitro assay indicated that AtPCS2 is capable to efficiently catalyze PCs biosynthesis. These results suggest that repression mechanisms exist in Arabidopsis to tightly control AtPCS2 function in vivo . To test and decipher this hypothesis, we generated the construct 35S/AtPCS2::cMyc and transformed it into the PCs-deficient mutant cad1 - 3 . Our results showed that both the AtPCS2 mRNA and protein levels were steadily high in the transgenic plants. Consistently, PCs biosynthesis and metal tolerance were also observed when AtPCS2 was introduced into cad1 - 3 . Furthermore, in addition to the cytosol, AtPCS2 was also localized to the nuclei. Taken together, all these results indicate that AtPCS2 is under tight control mainly at the transcription level in Arabidopsis , and it may function beyond catalyzing PCs biosynthesis.

We report on an efficient miniature Yb:CNGG disordered crystal laser, which is passively Q-switched with a Cr4+:YAG crystal plate acting as saturable absorber. An average output power of 1.35 W is generated at a pulse repetition rate of 5.55 kHz with a slope efficiency of 42%; the resulting laser pulse energy and duration are respectively 243 μJ and 3.0 ns, while the peak power is as high as 81 kW.

Anomalous passive Q-switching behavior was demonstrated in an Yb:KLu(WO4)2 laser, with a Cr4+:YAG crystal plate acting as saturable absorber whose initial transmission amounted to 99.3%. In stable Q-switched operation realized under high output coupling of 80%, 1.83 W of average output power was produced at a pulse repetition rate of 0.97 MHz, far beyond the upper limit imposed by the recovery time of the saturable absorber. The largest pulse energy, shortest pulse duration, and highest peak power were, respectively, 1.89 µJ, 39 ns, and 48.5 W. The high-repetition-rate passive Q-switching performance shows a close similarity to some Yb-ion lasers passively Q-switched by 2D saturable absorbers.

We report on a passively Q-switched coupled-cavity Yb:LuPO4 laser oscillating at 1005–1020 nm with a sapphire based few-layer WSe2 serving as saturable absorber. With 12.2 W of pump power absorbed, an average output power of 3.32 W is produced at a repetition rate of 1.34 MHz with a slope efficiency of 38%; the resulting pulse energy, duration, and peak power are respectively 2.5 µJ, 28 ns, and 89.3 W. These results demonstrate the great potential of few-layer WSe2 for use as saturable absorber in developing multi-watt, high-repetition-rate, nanosecond passively Q-switched solid-state lasers in the 1 µm spectral region.

Bread wheat (Triticum aestivum L.) is a hexaploid species with a large and complex genome. A reference genetic marker map, namely the International Triticeae Mapping Initiative (ITMI) map, has been constructed with the recombinant inbred line population derived from a cross involving a synthetic line. But it is not sufficient for a full understanding of the wheat genome under artificial selection without comparing it with intervarietal maps. Using an intervarietal mapping population derived by crossing Nanda2419 and Wangshuibai, we constructed a high-density genetic map of wheat. The total map length was 4,223.1 cM, comprising 887 loci, 345 of which were detected by markers derived from expressed sequence tags (ESTs). Two-thirds of the high marker density blocks were present in interstitial and telomeric regions. The map covered, mostly with the EST-derived markers, approximately 158 cM of telomeric regions absent in the ITMI map. The regions of low marker density were largely conserved among cultivars and between homoeologous subgenomes. The loci showing skewed segregation displayed a clustered distribution along chromosomes and some of the segregation distortion regions (SDR) are conserved in different mapping populations. This map enriched with EST-derived markers is important for structure and function analysis of wheat genome as well as in wheat gene mapping, cloning, and breeding programs.

Recently, cylindrical vector beams have drawn considerable attention for their interesting properties and potential applications in super-resolution optical imaging, optical trapping and manipulating. It’s easy to obtain inhomogeneous status of polarization by designing the diffractive optical elements particularly. With the change of the polarization of cylindrical vector beams, three dimensional (3D) flattop fields could be obtained. Numerical analysis shows that the full width at half maximum of the proposed 3D flattop light field is nearly 5λ for axial distributions. The result shows a potential application of the cylindrical vector beams in laser beam shaping system and laser cutting.

We propose a compact, high efficient full photonic crystal Mach-Zehnder interferometer based on the self-collimation and photonic band gap in a Rod-type Photonic Crystal. Line defected photonic crystals are used as the beam splitter and the mirror. Self-collimation frequency range is confirmed by employing the plane wave expansion method. The interference is investigated with the finite difference time domain simulation technique, and the simulation results agree well with the theoretical prediction. Because of their small dimensions, the proposed MZ interferometer hold great potentials for applications in photonic integrated circuits.

Fusarium species cause serious diseases in cereal staple food crops such as wheat and maize. Currently, the mechanisms underlying resistance to Fusarium-caused diseases are still largely unknown. In the present study, we employed a combined proteomic and transcriptomic approach to investigate wheat genes responding to F. graminearum infection that causes Fusarium head blight (FHB). We found a total of 163 genes and 37 proteins that were induced by infection. These genes and proteins were associated with signaling pathways mediated by salicylic acid (SA), jasmonic acid (JA), ethylene (ET), calcium ions, phosphatidic acid (PA), as well as with reactive oxygen species (ROS) production and scavenging, antimicrobial compound synthesis, detoxification, and cell wall fortification. We compared the time-course expression profiles between FHB-resistant Wangshuibai plants and susceptible Meh0106 mutant plants of a selected set of genes that are critical to the plants' resistance and defense reactions. A biphasic phenomenon was observed during the first 24 h after inoculation (hai) in the resistant plants. The SA and Ca(2+) signaling pathways were activated within 6 hai followed by the JA mediated defense signaling activated around 12 hai. ET signaling was activated between these two phases. Genes for PA and ROS synthesis were induced during the SA and JA phases, respectively. The delayed activation of the SA defense pathway in the mutant was associated with its susceptibility. After F. graminearum infection, the endogenous contents of SA and JA in Wangshuibai and the mutant changed in a manner similar to the investigated genes corresponding to the individual pathways. A few genes for resistance-related cell modification and phytoalexin production were also identified. This study provided important clues for designing strategies to curb diseases caused by Fusarium.

Efficient stable passively Q-switched operation of an Yb:CNGG disordered garnet laser is demonstrated with a GaAs crystal plate as the saturable absorber. An average output power of 1.76 W is produced at a pulse repetition rate of as high as 166.7 kHz, with optical-to-optical and slope efficiencies of 23.2 and 33%, respectively. The shortest pulse duration achieved was 99.5 ns.

We report on the passive Q-switching laser performance of the Yb:Gd3Ga5O12 garnet crystal. With a Cr4+:YAG crystal used as saturable absorber for passive Q-switching, an average output power of 5.31 W was produced at a pulse repetition rate of 62.5 kHz, the optical-to-optical and slope efficiencies being, respectively, 45% and 61%. Laser pulses of 140 μJ in energy and 5.8 ns in duration were also obtained at 22.2 kHz, with a corresponding peak power amounting to 24.1 kW.

It is reported that the fatigue intensity and fatigue life can be improved when the laser surface treatment is carried out on the test specimen made with class I blade material (1Cr11Ni2W2MoV stainless steel) of WP-6A engine compressor. By comparing with the tests, we can conclude that the fatigue life of the treated specimen is 2.13 to 4.01 times as long as that of the untreated, and that when the power densities of the laser are 8578 W/cm2 and 9446 W/cm2, the fatigue limits of the specimens have increased by 19% and 41%, respectively, and we find the relation between the multiplication value of fatigue life k and stress S.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.