Application Research Of Epsilon-Near-Zero Materials In Antenna Design

Epsilon-near-zero(ENZ)media,as one of the special metamaterials exhibits a number of extraordinary electromagnetic properties.The decoupling of spatial and temporal field variations results in the propagating wave inside materials with ENZ have the properties of infinite wavelength and phase velocity,and uniform spatial distributions of both the phase and field.Based on unique features,ENZ materials have been widely used in the fields of tailoring electromagnetic waves-matter interaction,and focus on applications of directed emission devices,integrated electro-absorption modulators,nonlinear optics,transmission waveguide devices and all-optical circuit boards.However,there are less passions on the applications of antennas with novel function,such as reconfigurable plasmonic antennas and deformation-independent flexible antennas by using ENZ materials.In this thesis,theoretical and experimental research works were carried out on the application research of epsilon-near-zero materials in antenna design.Here,we reviewed the research background and current studies of ENZ metamaterials,summarize the fundamental theory,and based on ENZ media,investigated the reconfigurable dual-wavelength molecular sensors,the coupling effects of plasmonic antennas and epsilon-near-zero modes,and deformation-insensitive curved antennas.The main contents and conclusions of the thesis are presented below:(1)Reconfigurable dual-wavelength refractive index(RI)sensor based on plasmonic antennas integrating ENZ materialsRI sensors have attracted considerable research interest due to detecting tiny RI changes.We proposed numerically a reconfigurable sensing platform by combination of waveguide modes and ENZ modes.Firstly,a dual-wavelength perfect absorber was obtained using an asymmetrical stacked metal-dielectric multi-layer structure integrating an ENZ nano-film by the excitation of waveguide modes and ENZ modes at1144 nm and 1403 nm,respectively.Effects of geometric dimensions on light absorption were also investigated and structural robustness was analyzed to guide the fabrication of the proposed device.Then,based on the electric field tuning of the ENZ properties of indium tin oxide(ITO),we proved a single-mode electro-absorption modulator with dual-wavelength.Finally,a dual-wavelength biosensor with high-performance was demonstrated by the case of glucose,and was amenable to miniaturization without prism coupler.Thus,the sensing platform exhibits potential applications on microfluidic systems,detectors and electro-absorption modulators.(2)The coupling effects of plasmonic antennas and ENZ modes,and its applications on the enhancement of absorption bandwidth for lightENZ mode can tailoring electromagnetic wave-matter interactions and achieve complex spectral shaping by coupling plasmonic resonance modes.Firstly,we utilized a plasmonic patch antenna integrating ITO ultra-thin film to obtain two polariton branches of reflection spectrum,and the calculated Rabi splitting of 34%,observing the strong coupling phenomenon of ENZ modes and gap plasmon modes.Then,we presented a new design strategy for enhancing broadband optical absorption by coupling ENZ modes to gap plasmon modes,light absorption over 99% was achieved within1400?1655 nm.Besides,the coupling strength of the two modes was investigated by varying thickness of dielectric layer of plasmonic antenna.Finally,using the carbon-based material with large optical absorption,we designed,fabricated and characterize solid photoacoustic(PA)lenses with high sensitivity respectively.The solid PA sensor with carbon/polydimethylsiloxane composite achieved a focal region of an ellipsoid with major axis of 230?m and minor axis of 90?m,and the ablation effect was demonstrated by scanning the focal point over gelatin gel phantom.(3)Deformation-and length-independent curved ENZ antennas based on substrate integrated waveguide(SIW)Radiation characteristics of the traditional antenna is closely related to its shape and dimension,which limits its application for integration.We summarize the structure and characteristics of SIW,proved that the SIW exhibited ENZ behavior at its cutoff frequency,and analyzed the width effect of SIW on ENZ parameter.Then,radiation characteristics of planar ENZ antenna based on SIW were investigated and demonstrated the working frequency was length-independent.The propagating electromagnetic wave within SIW with ENZ behavior exhibited infine phase velocity and uniform distributions of electric field.Based on the unique properties,we designed,fabricated and tested singly and doubly curved SIW-ENZ antennas with same apertures and different lengths.By comparing the radiation patterns of E plane and H plane,we obtained that the radiation characteristics of the two antennas with different shape and dimension are almost the same.The experimental results were in good agreement with the simulated results,and shown a level of low cross-polarization of curved SIW-ENZ antennas.Consequently,we proposed and verified a novel design platform of deformation-and length-insensitive flexible SIW-ENZ antennas.