Fano Resonance Of All-dielectric Metasurface And The Control Of Its Optical Properties

In the development of photonics,it is very important to realize high performance resonances to improve the characteristics of optical devices.Not depending on the phase different caused by the propagation and with size compressed to the wavelength level in the propagation direction,the metasurface devices made it possible to maniaturize and integrate modern optical applies.In order to effectively couple and control electromagnetic radiation,the all-dielectric metasurface provides a simple and effective platform,which is widely used in various technical fields.At present,Fano resonances with superior properties are realized by customizing the metasurface of micro-nano metastructures,however,there are often complex structural design and control process,and the further analysis of resonance regulation mechanism is still to be improved.In this paper,on the basis of all-dielectric metasurface by means of theoretical simulation and numerical simulation,three kinds of devices are designed and studied,which can realize high quality resonances and whose optical properties can be adjusted flexibly.A novel planar nanohole slab with tetramerized holes is deigned to obtain high quality factor dual-band Fano resonances based on the excitation of dual BICs in near-infrared region.By shrinking or expanding the tetramerized holes of the superlattice of the PNS,two symmetry-protected BICs can be induced to dual-band Fano resonances.Based on the analysis of the far-field multipole decomposition and the near-field electromagnetic field distribution,it is concluded that the dual-band Fano resonance is excited by the resonant coupling between the ED-TD or MD-TD modes.By increasing the height of the PNS,multiple Fano resonances with high Q-factors can be excited in the wavelength range.The device provides more tuning degrees of freedom for high Q-factor resonators with higher performances,and can provide further reference for the development of laser,sensing and nonlinear photonics.A high Q-factor polarization-dependent Fano resonance based on BIC in the near infrared region excited by a Si based all-dielectric metasurface is proposed.The nanostructure includes a Si-nanoblock-arrays deposited on a SiO₂substrate.By shifting one of the Si blocks along the axis,Fano resonances with high Q factor at different wavelength positions under x and y polarized incidence conditions can be excited.Based on the analysis of far-field multipole decomposition and near-field electromagnetic field distribution,two Fano resonances are mainly contributed by TD mode and MD mode,respectively.The change of the translational symmetry in the structure supercell regulates the two resonance optical properties,and the dual channel Fano resonances can be realized during the conversion of the incident polarization angle.The breaking of mirror symmetry can also excite different Fano resonances related to polarization.The design of the metasurface is simple and the structral parameters are easy to fabricate,which provides the possibility for miniaturization and integration of modern optical devices.A resonance dynamic tuning based on the metasurface of Si disk arrays is proposed.Dual-channel Mie resonance in near-infrared region are excited by Si disk structure on SiO₂substrate.The in-plane asymmetry of the structure is broken by changing the horizontal and vertical contrast of the Si disks,and the resonance positions and the bandwidths of the dual-channel resonance are regulated.Based on the analysis of far-field multipole decomposition and near-field electromagnetic field distribution,the dual-channel resonance is mainly contributed by ED mode and TD mode,respectively.The dual-channel Fano resonance is produced in the background of Mie resonance under oblique incidence,and is modulated with the change of oblique incidence degree.The Si/GST hybrid metasurface is reconstructed and the dual-channel Mie resonance is dynamically controlled by using the dynamic reconfigurable property of phase change material,controlling the depth of resonance modulation during the transition between amorphous and crystalline state.The structure is simple and easy to fabricate,which provides theoretical basis and potential value for the applications of perfect reflector and magnetic mirror.