High-security nondeterministic encryption communication based on spin-space-frequency multiplexing metasurface

Information security plays an important role in every aspect of life to protect data from stealing and deciphering.However,most of the previously reported works were based on pure algorithm layer or pure physical layer encryptions,which have certain limitations in security.In this paper,a nondeterministic message encryption communication scheme is proposed based on a spin-space-frequency multiplexing metasurface(SSFMM),which integrates both algorithmic and physical layer encryptions,and can also produce multiple different ciphertexts for the same message to prevent the message from being cracked through frequency analysis,thus greatly enhancing the security of the information.To be specific,an SSFMM is first designed as a physical-layer meta-key,which can generate eight independent dot matrix holograms with different spin,space,and frequency characteristics.The target message is then encrypted based on these dot matrix holograms combined with algorithmic operations,and the encrypted message is converted into a quick response(QR)code for easy sending to the target users.Once the target user gets that QR code,he/she can scan it to obtain the encryption information,and then recover the target message according to the pre-agreed encryption protocol combined with the eight dot matrix holograms of SSFMM.Finally,the feasibility of the proposed encryption scheme was experimentally validated at the microwave frequency band.

Surface engineering of highly ordered Bi_(2)S_(3) film with open channels toward high-performance broadband photodetection

The highly ordered film assembled by regularly 1D nanostructures has potentialprospects in electronic,photoelectronic and other fields because of its excellentlight-trapping effect and electronic transport property.However,the controlledgrowth of highly ordered film remains a great challenge.Herein,large-area andhighly ordered Bi_(2)S_(3) film is synthesized on fluorophlogopite mica substrate bychemical vapor deposition method.The Bi2S3 film features hollowed-outcrosslinked network structure,assembled by 1D nanobelts that regularly distributein three orientations,which agrees well with the first principles calculations.Based on the as-grown Bi_(2)S_(3) film,the broadband photodetector with a responserange from 365 to 940 nm is fabricated,exhibiting a maximum responsivity upto 98.51 mA W^(–1),specific detectivity of 2.03×10^(10)Jones and fast response timeof 35.19 ms.The stable instantaneous on/off behavior for 500 cycles and reliablephotoresponse characteristics of the Bi_(2)S_(3) photodetector after storage in air for6 months confirm its excellent long-term stability and air stability.Significantly,as sensing pixel and signal receiving terminal,the device successfully achieveshigh-resolution imaging of characters of“H”,“I”and“T”,and secure transmissionof confidential information.This work shows a great potential of the largeareaand highly ordered Bi_(2)S_(3) film toward the development of future multiplefunctional photoelectronic applications.