Broadband high-efficiency dielectric metalenses based on quasi-continuous nanostrips

Benefiting from the abrupt phase changes within subwavelength thicknesses,metasurfaces have been widely applied for lightweight and compact optical systems.Simultaneous broadband and high-efficiency characteristics are highly attractive for the practical implementation of metasurfaces.However,current metasurface devices mostly adopt discrete micro/nano structures,which rarely realize both merits simultaneously.In this paper,dielectric metasurfaces composed of quasi-continuous nanostrips are proposed to overcome this limitation.Via quasi-continuous nanostrips metasurface,a normal focusing metalens and a superoscillatory lens overcoming the diffraction limit are designed and experimentally demonstrated.The quasi-continuous metadevices can operate in a broadband wavelength ranging from 450 nm to 1000nm and keep a high power efficiency.The average efficiency of the fabricated metalens reaches 54.24%,showing a significant improvement compared to the previously reported metalenses with the same thickness.The proposed methodology can be easily extended to design other metadevices with the advantages of broadband and high-efficiency in practical optical systems.

Flat multifunctional liquid crystal elements through multi-dimensional information multiplexing

Flat optical elements have attracted enormous attentions and act as promising candidates for the next generation of optical components.As one of the most outstanding representatives,liquid crystal(LC)has been widely applied in flat panel display industries and inspires the wavefront modulation with the development of LC alignment techniques.However,most LC elements perform only one type of optical manipulation and are difficult to realize the multifunctionality and light integration.Here,flat multifunctional liquid crystal elements(FMLCEs),merely composed of anisotropic LC molecules with space-variant orientations,are presented for multichannel information manipulation by means of polarization,space and wavelength multiplexing.Specifically,benefiting from the unique light response with the change of the incident polarization,observation plane,and working wavelength,a series of FMLCEs are demonstrated to achieve distinct near-and far-field display functions.The proposed strategy takes full advantage of basic optical parameters as the decrypted keys to improve the information capacity and security,and we expect it to find potential applications in information encryption,optical anti-counterfeiting,virtual/augmented reality,etc.

Internal States Influence the Representation and Modulation of Food Intake by Subthalamic Neurons

Deep brain stimulation of the subthalamic nucleus(STN)is an effective therapy for motor deficits in Parkinson’s disease(PD),but commonly causes weight gain in late-phase PD patients probably by increasing feeding motivation.It is unclear how STN neurons represent and modulate feeding behavior in different internal states.In the present study,we found that feeding caused a robust activation of STN neurons in mice(GCaMP6 signal increased by 48.4%±7.2%,n=9,P=0.0003),and the extent varied with the size,valence,and palatability of food,but not with the repetition of feeding.Interestingly,energy deprivation increased the spontaneous firing rate(8.5±1.5 Hz,n=17,versus 4.7±0.7 Hz,n=18,P=0.03)and the depolarization-induced spikes in STN neurons,as well as enhanced the STN responses to feeding.Optogenetic experiments revealed that stimulation and inhibition of STN neurons respectively reduced(by 11%±6%,n=6,P=0.02)and enhanced(by 36%±15%,n=7,P=0.03)food intake only in the dark phase.In conclusion,our results support the hypothesis that STN neurons are activated by feeding behavior,depending on energy homeostatic status and the palatability of food,and modulation of these neurons is sufficient to regulate food intake.