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Cylindrical vector beams (CVBs) with unique spatial polarization states have attracted great interest in recent years. However, the generation of high-power CVBs faces a significant challenge due to the limited output power of a single laser. Here, we capitalize on the brightness enhancement offered by coherent beam combining (CBC) technique and propose an architecture for generating arbitrary CVBs based on a CBC system. The phase noise is effectively compensated using an all-fiber internal phase-locking technique. By designing the polarization direction of each beamlet in the laser array, the desired mode of CVB can be generated. This work could provide a reference for generating high-power CVBs. [ABSTRACT FROM AUTHOR]

Perfect vortex beams (PVBs) possess the advantage of a stable light field distribution regardless of their topological charges, and thus they are extensively utilized in various applications, such as free-space optical communication, optical tweezers and laser processing. Herein, we report a new strategy to generate and modulate PVBs using coherent beam combining (CBC) technology. Both piston phase and tilting phase controlling methods have been successfully employed, and the corresponding properties of the generated PVBs have been fully investigated. Moreover, the number and position of the gaps in fractional perfect vortex beams (FPVBs) could be precisely controlled, and the relationships between these modulated parameters and the performance of FPVBs are uncovered. These simulation analysis results demonstrate the potential for flexible modulation of PVBs or FPVBs in the CBC system, indicating promising prospects for coherent beam arrays (CBAs) in laser beam shaping and achieving high-power structured light. [ABSTRACT FROM AUTHOR]

Leaf is the main organ of photosynthesis. Leaf phenotypic plasticity largely determines the adaptation of plants to enriched nitrogen (N) environments. However, it remains unclear whether the optimal number (proportion) of leaves representing the leaf traits of the whole plant is similar between ambient and N-enriched conditions. Moreover, whether alteration in ammonium (NH4+-N) to nitrate (NO3−-N) ratios in atmospheric N deposition will alter the optimal leaf number is unexplored. By adding three NH4+-N/NO3−-N ratios in a temperate grassland of northern China since 2014, three traits (leaf area, thickness and chlorophyll content) of two dominant clonal grasses, Leymus chinensis and Agropyron cristatum , were measured in August 2020. Results showed that under ambient conditions, the mean leaf area, thickness and chlorophyll content values of two fully expanded leaves were similar to these of all leaves at the plant level, except for the leaf area of L. chinensis , which needed five leaves (78.82% of leaves in the plant). The ratios of NH4+-N/NO3−-N increased the number of required sampled leaves and significantly changed the mean value of leaf traits and the maximum value along leaf order. Moreover, the ratios of NH4+-N/NO3−-N altered the trade-off among the three leaf traits, which is dependent on leaf order, by increasing leaf area and decreasing leaf thickness. Therefore, our study suggests that to better indicate the leaf traits' value of the whole plant under N-enriched conditions, measuring all fully expanded leaves or providing a suitable scaling-up parameter is needed. [ABSTRACT FROM AUTHOR]