Research On Spectral Property And Structral Design Of Micro-and Nano-structrued Metamaterial

In recent years,metamaterials have been thought to be a novel technology dealing with rapid consumption of traditional energy and urgent demand of revolution in high-tech industry.The modification and tailoring of optical spectra through elaborate design of micro-and nano-sized metamaterial structures are required in lots of optical devices,like optical sensor,optical switch,optical metasurface,nano-lens,and nano-antenna.Micro-and nano-sized metamaterial structures possess various of spectral characteristics,which provide much design space for nano-optical devices.The main effort of this work is to realize specific optical spectra through adjustment or modification over metamaterial structures for the further design of optical devices.Our work include:(1)The design of metamaterial solar absorbers.Micro-and nano-sized optical structures can be applied in solar-thermal conversion systems.In this paper,three nano-structures are proposed to realize high-efficiency solar absorption.Theoretical results show that over 90%absorbing efficiency is achieved for these structure.Iron is used as the absorbing material and is proved to possess high broadband absorption efficiency.Besides,moth-eye structure and lossy semiconductor materials are cooperated for the design of novel selective solar absorber,which presents unique properties such as near-perfect selective absorbing ability,insensitivity to incident angles,and tunable absorbing wavelength.(2)The study of scattering performance of nano-structures and directional scattering phenomena.Scattering performances of nano-structures are studied to realize the resonant and the non-resonant Kerker directional scattering effect.We propose the realization of directional scattering based on quadrupole resonances through geometry control over nano-particles.The methods to realize directional scattering with specific angles in scattering plane are concluded.We further propose the method to realize directional scattering with scattering angles out of scattering plane.(3)The study of spectrum responses of periodical nano-particle array.The electromagnetic induced transparency based on high-order quadrupole modes is realized for the first time.A dark-mode magnetic quadrupole resonance is excited in a symmetric structure to realize high-quality Fano spectrum.The Fano peaks possess extreme narrow bandwidth and its quality factor can reach 2×105,which is the highest value reported in dielectric Fano resonant systems by far.Such spectrum can be applied for optical switch and optical sensing.(4)The study of phase spectrum of nano-structures and the design of novel metasurfaces.In this work,we propose two design strategies of novel Huygens' metasurface dealing with some defects of traditional Huygens'metasurfaces.The first method used is to add an extra optimization process on the element spacing and element parameters of a Huygens' metasurface to correct the phase distortion resulting from element interaction.Applying this method,a Huygens' metasurface with only three elements is realized.Another way is to adopt quadrupole modes to realize Huygens' metasurface.Owing to the insensitivity to multipole interaction,quadrupoles-based Huygens' metasurface shows insensitivity to the periodicity.In this paper,the physical origination and excitation conditions of many electromagnetic resonances are concluded and differentiated,which provide sufficient physical supports for optical spectrum designs.High-efficiency nano-structures and metasurfaces are designed in this article,which help to develop high-efficiency optical devices.Our results can be applied in a lot of applications like clean energy,energy saving,optical communication,and optical chip.Our work promotes the development of efficient,miniaturized,controllable,high-integrated optical devices.