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A super-resolution imaging technique based on the vortex electromagnetic (EM) wave, which carries orbital angular momentum (OAM), is reported in this paper. The proof-of-concept experiment for the EM vortex imaging is conducted. An imaging processing method based on the real-world OAM radar data is proposed to obtain the target profile. Experimental results validate the effectiveness of the proposed imaging method and demonstrate that the vortex EM wave can be exploited to image targets with high-resolution beyond the limit of the array aperture. This breakthrough on the Rayleigh limit paves the way for innovative techniques in radar imaging and remote sensing.

An unprecedented Ag(i)-catalyzed ligand-controlled stereodivergent 1,3-dipolar cycloaddition of azomethine ylides with 3-methyl-4-nitro-5-styrylisoxazoles has been developed to afford heterocycles bearing both methylisoxazole and pyrrolidine moieties. The endo- and exo-cycloadducts were obtained in good yields with excellent stereoselectivities, assisted by (t)Bu-Phosferrox and phosphoramidite as chiral ligands, respectively.