The Research On Metal Optical Antennas And Its Related Device

The optical antennas received broad interest in optics related fields since its first emergence.As optical antennas can manipulate electromagnetic wave as traditional antennas,but also introduced new physical meaning due to its sub-wavelength dimension.Physical characteristics of optical antennas can be classified into mainly four aspects: near-field enhancement,losses and absorption for electromagnetic wave in optical range,manipulation of electromagnetic wave's properties in optical range and the light-thermal effect.So the purpose of this dissertation is to investigate the four aforementioned properties of optical antennas and to propose application device implementing them.This dissertation can be summarized as following aspects:(1)We put forward a MIM(metal-dielectric-metal)absorber structure in the infrared range with split cross antennas.This structure arranged four metallic nanorods in the shape of 'X' as the antenna array with dielectric spacer and metallic back plate bellowing.We used numerical simulation software(COMSOL multiphysics)for analysis of different geometry parameters' tuning effects on the spectrum response.Implementing this structure's narrow absorption linewidth and near-filed enhanced,we move on and study its application as a refractive index sensor.The optimized antenna parameters achieve a narrow linewidth of 39 nm and a peak absorption efficiency of 96.5% at a resonance wavelength of 3.17 ?m.The optimized plasma absorber can achieve 988/RIU sensitivity at the single wavelength in the spectral displacement sensing mode.The quality factor in the sensor mode is as high as 3082.(2)We present the design of an electric-tunable optical absorber based on piezoelectric effect,and analyze the mechanism and modulation depth of presented piezoelectric tunable micro optomechanic cavity.Then we come up with a device with the manipulation on the polarization state of spatial light based on this structure.The FWHM of the absorption peak at a wavelength of 2.58 ?m was 33 nm.The voltage-driven piezoelectric film regulates,and as the voltage becomes larger,the absorption peak of the optical antenna can be linearly increased.A wavelength increase of 250 nm can be achieved with a voltage variation of 10 V.And when the duty ratio of the optical antenna is greater than 0.9,only 1V driving voltage is required to achieve a 75% absorption rate at a fixed wavelength.(3)We designed an antenna-compacted thermal deformation and polarization state detector.The structure can absorb incident infrared light depending on its polarization state,which is enabled by the light thermal effect of optical antennas with selectivity of incident light polarization state embedded in two different material layers.According heat cause the deformation in the structure due to different inflation constant of the two layers.We performed systematically analysis on the antenna structure's spectrum device,and the device's thermal noise,background noise and vibration noise,and designed an antenna integrated pixel array detector based on such thermal deformation sensitive structure.The integrated nano-antenna was tuned to achieve maximum absorption at 6 ?m,and a bi-layer film cantilever structure using PMMA and silicon nitride materials was studied to achieve optimal response and noise performance.(4)We put forward an antenna based pyroelectric infrared detector.The LiTaO3 film is used as the heat-sensitive material,and an MIM style optical antenna array is fabricated on the surface of the film through typical semiconductor fabrication process.The relationship between the spectral characteristics and the geometrical parameters of the antenna is systematically analyzed and we optimize the fabrication process.Then we conduct characterization using Fourier transform infrared spectroscopy(FTIR),which is for measurement of absorption spectrum of the sample,and scanning electron microscopy(SEM),measuring sample's morphology and finally make comparison with the simulation model's parameters.We also studied transient or steady-state thermal response of this structure,performed the signal current power theoretical calculation,and how other factors influence the device's performance.The theoretical calculations,and discussed various factors that influence the performance of the device.