Since the celebrated twist phase was proposed by Simon and Mukunda, despite the tremendous progress made in theory over the past decades, developing a simple and flexible experimental method to customize this novel phase has long been a tricky challenge. In this Letter, we demonstrate a general experimental method for generating twisted Schell-model beams by implementing the continuous coherent beam integral function in a discrete form. Experimental results based on rigorous Laguerre–Gauss modes superposition are also demonstrated, indicating that our method is more convenient and of higher quality. The twist factor is also measured using the rotation characteristics during propagation, and the results agree well with the theoretical prediction. The method could serve as a general way for customizing bona fide twisted cross-spectral densities while facilitating certain applications.

Pulsed laser ablation in liquid (PLAL) is gradually becoming an attractive approach for nanomaterial fabrication because it is a chemically simple and clean method with high product purity. We studied the laser interaction with bulk target and particle products in detail, including mechanism process, target morphology and nanoparticle products. We captured three oscillations of one bubble after laser ablates the bulk target and calculated the variation of pressure and temperature inside the bubble. The results show that the first bubble oscillation has greatest impact on the nanomaterial synthesis, and the most powerful stages for the material synthesis during all the bubble oscillations are the beginning of each expansions and the end of each shrinks. Nanomaterial releases from the bubble at the end of each oscillations. In addition, based on the analysis of ablation cavity on the target, it is found that the cavity depth increases with the number of laser pulses, and then the depth tends to be under saturation status, which means it is difficult to obtain great improvement of the nanomaterial productivity just by prolonging the laser irradiation time. More importantly, the strong interaction between laser and particle products is presented clearly by time-resolved shadowgraphy, which can contributed to the modification of nanoparticle products.

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A flexible pseudo-mode sampling superposition method for synthesizing partially coherent sources has been introduced that can be thought of as an approximate discrete representation of Gori’s nonnegative definiteness criterion for designing spatial correlation functions. Importantly, without performing formidable mode analysis, this method enables us to develop a convenient and efficient experimental technology to customize partially coherent sources without sacrificing theoretical accuracy. As an example, we experimentally generate a new, to the best of our knowledge, class of nontrivial pseudo-Schell model sources recently proposed by de Sande et al. Our approach opens up a useful avenue for manipulating nontrivial partially coherent beams and promotes applications for optical tweezers and photolithography.

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The mechanical properties, thermal properties, electronic structures, and optical properties of the defect perovskites Cs 2 SnX 6 (X = Cl, Br, I) were investigated by first-principles calculation using PBE and HSE06 hybrid functional. The optic band gaps based on HSE06 are 3.83 eV for Cs 2 SnCl 6 , 2.36 eV for Cs 2 SnBr 6 , and 0.92 eV for Cs 2 SnI 6 , which agree with the experimental results. The Cs 2 SnCl 6 , Cs 2 SnBr 6 , and Cs 2 SnI 6 are mechanically stable and they are all anisotropic and ductile in nature. Electronic structures calculations show that the conduction band consists mainly of hybridization between the halogen p orbitals and Sn 5s orbitals, whereas the valence band is composed of the halogen p orbitals. Optic properties indicate that these three compounds exhibit good optical absorption in the ultraviolet region, and the absorption spectra red shift with the increase in the number of halogen atoms. The defect perovskites are good candidates for probing the lead-free and high power conversion efficiency of solar cells.

The electronic structure shows that FAVI3 is a novel organic–inorganic hybrid perovskite-type spin gapless semiconductor.