The Research Of Mid-infrared Super-resolution Imaging Based On Metallic Nanoarray

In recent years, optical imaging technology has made great breakthrough, and its applications are more widely. For all most conventional imaging system, the imaging resolution is limited by the diffraction limit and it is difficult to realize the nanoscale super-resolution imaging. To this problem, a series of metallic nanoimaging model based on the plasmonics is proposed for super-resolution imaging. Due to the unique characteristics of the plasmon, such metallic nanoimaging models can break the diffraction limit and have the ability of super-resolution imaging at the ultraviolet, visible and near infrared wavelengths, respectively. Moreover, the resolution has greatly improved. However, due to the difficulty of the tunability, these metallic nanoimaging models did not realize mid-infrared super-resolution imaging.This paper investigates the optical property of the unique metallic nanorod-bridged dimer by using the numerical simulation method. The metallic nanorod-bridged dimer is composed of the metallic nanorod dimer which is connected end-to-end by a thin metallic conduction. The results show that a charge transfer plasmon(CTP) resonance emerge and the resonance wavelength of CTP mode can be tuned in the mid-infrared region. Based on this, the metallic nanorod-bridged dimer array is designed with the fixed size metallic nanorod-bridged dimer. Then we investigate the super-resolution imaging with the metallic nanorod-bridged dimer array by using the numerical simulation method When the incoherent dipole source and coherent dipole source are as an object, respectively, we calculate the field intensity distributions at the source plane and the image plane with the different array pitch. The simulation results show that the proposed metallic nanoarray has been able to achieve super-resolution imaging of incoherent dipole source and coherent dipole source at mid-infrared wavelengths. The image quality is sensitively dependent on the source coherent, the distance from the image plane to the array and the array pitch. In the same structural parameters, the image quality of incoherent source is higher than that of coherent source of in-phase. The operation wavelength is the CTP resonance wavelength of 4390 nm, the spatial resolution of 40nm(λ/109) and 60nm(λ/73) is obtained corresponding to the incoherent imaging case and coherent imaging Meanwhile, increasing the image-array distance and decreasing the array results in the lower image quality. Moreover, the results also show that the imaging array is capable of realizing broadband imaging around the resonance wavelength. The proposed metallic nanoarray is useful for some applications, such as biomedical imaging and sensing.