Study On The Property Of Super-resolution Of The Subwavelength Structure Based On Metal-dielectric

The ever-increasing demand for faster information transport and processingcapabilities has driven enormous progress in the microfabrication technology. Wehave witnessed a contiuous progression towards smaller, faster, and more efficientelectronic devices. The scaling of these devices has also brought about a myriad ofchallenges associated with electronic interconnection. On the other hand, a candidatetechnology has recently emerged and has been termed plasmoncis‘. As we know,due to the diffraction limit, the resolving power of traditional lithography waslimited at half of wavelength. However, for plasmonic nanolithography based onmetal-dielectric subwavelength structure, surface plasmon polaritons (SPPs) as aspecial type of light wave would be excitated and propagate along themetal-dielectric interface. Even the novel optical properties show that plasmonicnanostructure could break the diffraction limit. It means that the resolving power ofplasmonic nanolithography can be infinitesimal theoretically. Thereby mergingphotonics and electronic at nanoscale dimensions can be attained by integratingplasmonic, electric, and conventional photonic devices on the same chip, whichshould facilitate manufacture. Unfortunately, plasmonic nanolithography technologypresents some challenges, such as focal spot being not perfectly symmetrical, spacebetween the direct write array and wafer stage hardly being controled at nanometeraccuracy, and low efficiency in the production process.For these problems, we are interesting to propose a metallic subwavelength structure, which was called plasmonic nanolens. In the beginning, the influence ofstructural parameters on focusing properties was analysed by using finite differencetime domain (FDTD).Generally, an elliptical focal spot is obtained under linear ploarized light, toovercome this problem, the radially polarized light was used in our FDTD numericalsimulation for obtaining circular focal spot, and the Talbot effect of plasmonicnanolens was discovered. Then it is found that the Talbot effect can be observed onconditon that the incident wavelength is smaller than half of the period of thenanolens.Subsequently, an Al nanolens was fabricated by focused ion beam (FIB)technology, and by near-field scanning optical microscopy (NSOM) the plasmonicTalbot effect was proved iulluminating by linearly polarized light.Finally, to improve the resolving power, we considered an immersion plasmonicstructure. The focusing properties of nanolens being immersed in H2O, SiO2, andAl2O3were studied. Moreover, the influence of metal material and incidentwavelength on super focusing properties was researched. And a circular focal spotwith diameter of a quarter of incident wavelength was obtained, which break throughdiffraction limit.The super resolution properties of plasmonic nanolens could beexpected to apply in various fields including nanolithgraphy, near field microscopy,sensing, and data storage.