A nanometeric plasmonic filter with a symmetrical multiple-teeth-shaped structure is investigated theoretically and numerically. A tunable wide bandgap is achievable by adjusting the depth and number of teeth. This phenomenon can be attributed to the interference superposition of the reflected and transmitted waves from each tooth. Moreover, the effects of varying the number of identical teeth are also discussed. It is found that the bandgap width increases continuously with the increasing number of teeth. The finite difference time domain method is used to simulate and compute the coupling of surface plasmon polariton waves with different structures in this Letter. The plasmonic waveguide filter that we propose here may have meaningful applications in ultra-fine spectrum analysis and high-density nanoplasmonic integration circuits.

A new filter structure and optical field modulator with ultra-high resolution based on plasmonic nano-cavity resonators is proposed and numerically investigated. The structure consists of a square nano-cavity resonator connected with several waveguides. All waveguides and cavity are etched on a silver film whose size is 1.1×0.75  μm. Compared with traditional filters, the FWHM (full width at half-maximum) of this structure's spectrum curve can be less than 7 nm; namely, the resolution has been greatly improved. The structure also presents the feature of an optical field modulator when both inputs are working simultaneously, and it provides a promising way to design and manufacture future optical logical device.

The epidemic of coronavirus disease 2019 (COVID-19) broke out in Wuhan, China, in early 2020. In an effort to curb the spread of the epidemic, the government has requisitioned a variety of venues and plant buildings and built more than 20 cabin hospitals to receive patients with mild symptoms within 48 hours. Under this circumstance, we worked out a 5G all-wireless solution to divide the overall network system of the cabin hospital into multiple network units by function. While ensuring good signal coverage of the local unit, each network unit was independently connected to the host hospital’s data center over a virtual private network (VPN) tunnel built on the 5G wireless network. Our successful experience with the application of this 5G + VPN all-wireless network system well points to the bright prospect of 5G wireless network. In addition, the 5G + VPN solution can also be used for multihospital network interconnection and rapid network recovery during the failure of wired network.

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