Exploring optical resonances of nanoparticles excited by optical Skyrmion lattices.

Recently, optical Skyrmion lattices (OSLs) have been realized in evanescent electromagnetic fields. OSLs possess topologically stable field configurations, which promise many optics and photonics applications. Here, we demonstrate that OSLs can serve as versatile structured optical near-fields to assist with studies of a variety of photonic modes in nanoparticles. We firstly show that OSL is capable of selectively exciting electric and magnetic multipole modes by placing a nanoparticle at different positions in the lattice. We then disclose that OSLs can efficiently excite some intriguing resonant modes, including toroidal and plasmonic dark modes, in dielectric or metal nanoparticles. Our results may enhance understanding of the interaction between OSLs and nanoparticles and find applications associated with precise control over resonant modes in nanostructures.

Unidirectional excitation of plasmonic waves via a multilayered metal-dielectric-metal Huygens' nanoantenna.

Huygens' nanoantennas maintain orthogonal electric and magnetic dipole resonances satisfying the Kerker condition and can generate directional radiation in both the near-field and far-field regimes. Here we study a multilayered metal-dielectric-metal (MDM) Huygens' type nanoantenna which is capable of launching surface plasmon polaritons (SPPs) unidirectionally when excited by a dipole source. We show that the radiative decay rates of the dipole source are strongly enhanced by the antenna, and the generated SPP waves propagate in opposite directions at two different wavelengths. The directionality of the excited SPPs can be switched by changing the geometry and the material composition. We further demonstrated that the beam width of the SPP waves can be narrowed by arranging the MDM antennas in a chain.

Dual-band unidirectional forward scattering with all-dielectric hollow nanodisk in the visible.

High-index dielectric nanoantennas have become an emerging branch of optical nanoantennas, essentially due to their low loss. These types of nanoantennas can achieve both forward and backward unidirectional scattering, enabled by electric dipole and magnetic dipole interaction. Here, we show that the scattering directionality can be further enhanced if higher-order moments are properly balanced and reach the generalized Kerker condition at two different wavelengths in an all-dielectric hollow nanodisk. Moreover, putting the nanodisks in an array of transverse configuration can enhance the unidirectionality to be needle-like, with the main lobe angular beam width α<15°. Finally, we show that such unidirectional radiation properties can be maintained for a local electric dipole source.

[Explanation on bloodletting mechanism of scraping therapy].

On the base of acupuncture techniques in Chinese medicine, locations, apparatus and manipulation of scraping are analyzed in this article. It is held that scraping, no matter with the location, tools and manipulations of application, meets the requirements of shallow stimulation on collaterals described in Huangdi Neijing (Huangdi's Internal Classic). And the methods of scraping to cause shazhen (subcutaneous hemorrhage showed in scattered red spots on the skin) to eliminate pathogens in collaterals is also approved to meet the mechanism of Chinese medicine which expels pathogens with bloodletting. Therefore, it is held that scraping is a complete treating technique of shallow stimulation on collaterals.