| Electronic devices have attracted great attention and research in the past few centuries.However,the development of electronic devices will suffer from density limit and speed limit in the future.Different from electronic devices,photonic devices have a better application potentiality with advantages of high speed and low loss.The studies on light manipulation properties of micro/nanostructures have become a hot topic and trend.In this dissertation,the light manipulation by all-dielectric micro/nanostructures is studied.At present,the development and application of metasurfaces formed by all-dielectric micro/nanostructures are limited by small scale and high cost in fabrication.It is an urgent problem to fabricate metasurface with large area and dynamic adjustment.In this dissertation,a new metasurface fabrication and dynamic adjustment are presented.For the photonic nanojet（PNJ）formed by microstructures,the super-resolution imaging based on microscale structures is studied,and a new real-time dynamic adjustment of photonic nanojet is proposed.The innovation points of this dissertation are summarized as follows:1.In this dissertation,for the first time to our knowledge,an AAO template is combined with Ti O2metasurface fabrication with advantages of large area and low cost.One challenge of all-dielectric metasurfaces is the high cost and limited scale in fabrication,such as FIB and EBL lithography.A combination of Anodized Aluminum Oxide（AAO）Template and electron beam evaporation is used to fabricate the Ti O2metasurface.The limit of small scale of metasurface is overcome,and a large-area metasurface（more than 2cm2）is realized.Mie resonances of Ti O2metasurface appear in the visible spectrum.Furthermore,we demonstrate the interaction of the Cs Pb Br1.5I1.5quantum dot（QD）emission with Mie resonance of Ti O2metasurface,revealing that the metasurface exhibits remarkable photoluminescence（PL）enhancement of 25%.2.We propose a method to realize a dynamic metasurface with large area.All-dielectric metasurfaces are usually limited by static function.Most presented metasurfaces are based on static designs,their functionality can not be changed once the structures are fabricated.Different from the previous studies,the Si metasurface embedded in PDMS is fabricated based on the combination of aluminum oxide template method and electron beam evaporation.With an AAO template as evaporation mask,a large-area metasurface embedded in PDMS is fabricated after a process of Si vapor deposition and sacrificial layer dissolution.Based on the expansion characteristics of PDMS in toluene solution,the dynamic transmission spectrum of all-dielectric metasurface is realized.Our experiment reveals that,after immersion of toluene with 20%concentration,a red shift around 40 nm is achieved.3.Direct laser writing（DLW）lithography is used to produce a series of complex microstructures,which are capable of forming photonic nanojet and achieving super-resolution imaging.The practical field of view（FOV）of super-resolution based on microspheres is limited to only a few microns.So far,the realization of the natural microspheres with precise positioning still remains difficult.The microstructures printed by the DLW can easily align the limited FOV precisely within a desired location.Four kinds of complex micron-size structures,including cylinder,truncated cone,hemisphere and protruding hemisphere,are fabricated by this 3D printing technology,and 100 nm beyond diffraction limit is resolved.Therefore,combining such imaging capacities with the 3D printing technology represents a major step toward ubiquitous nanoscopy.4.We propose a switchable photonic nanojet produced by a polystyrene（PS）microsphere immersed in nematic liquid crystals（NLCs）.Although there have been many studies for tuning the PNJ properties using different size,material,geometry of spheres or core-shell spheres,they are an almost passive tunable process.Once the structures are designed and fabricated,their PNJ properties cannot be changed.The PNJ can be switched off or on by tuning the refractive index of NLCs larger or smaller than that of the PS microsphere.In addition,we also propose a series of optimization methods to seek a better electric energy focusing property of PNJ.This dissertation provides the experimental and theoretical basis for studying the light manipulation properties of dielectric micro/nanostructures.Based on the studies on metasurface fabrication with large area,dynamic metasurface with large area,photonic nanojet formation and switchable photonic nanojet,this research shall also pave a new route for hologram,light switch and biomedical sciences. |
