A Drude-Two-CP-FDTD method for Drude-critical points model of metal nanofilms
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A Drude-Two-CP-FDTD method for Drude-critical points model of metal nanofilms Jian-Xiao Liu1,2,3 , Yan Jiang2 , Ling-Hui Ming1, Wan-Chun Tang2,a , Hong-Wei Yang3,b 1 College of Electronics and Information Engineering, Hengshui University, Hengshui 053000,
People’s Republic of China
2 School of Physics Science and Technology, Nanjing Normal University, Nanjing 210023,
People’s Republic of China
3 Department of Physics, College of Science, Nanjing Agricultural University, Nanjing 210095,
People’s Republic of China Received: 22 June 2020 / Accepted: 1 October 2020 © Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Based on Drude-critical points (Drude-Two-CP) model for a dispersive media, a finite-difference time-domain (FDTD) method for metal nanofilms is proposed. By establishing the corresponding relationship between Drude-Two-CP model and Drude–Lorentz model, the conversion coefficients between the two models are calculated. And we modify the Drude-Two-CP model into the form of standard Lorentz model. The transformation relationship between the two models is conducive to the modular programming of FDTD. Formula deduction and calculation results show that Drude-Two-CP model has higher fitting accuracy and fitting formulas are more complex. Using the proposed FDTD method, we have calculated the reflection, transmission and extinction coefficients of gold and aluminium nanofilms. The results show that the FDTD results are in good agreement with those of Drude-Two-CP model, which are better than those of Drude–Lorentz model. Therefore, the Drude-Two-CP-FDTD method proposed in this paper is helpful for improving the accurate modelling and calculation of nano-optical structures.
Introduction With the rapid development of nanotechnology and the maturity of experimental technology, fine nanostructures can be easily manufactured by using laser technology. This lays a foundation for the development of nano-optics. When light incident on metal nano-surface, the interaction between electrons and photons on metal surface arises oscillation, meanwhile producing an electromagnetic wave spread along metal surface, which is called surface plasma [1–5]. At present, surface plasma has been used in photoelectric sensors, optical waveguides, optical grating and others [6–8]. Metal nanostructure is an important part of nano-optics. Therefore, how to effectively simulate the photoelectric characteristics of different metal
Hong-Wei Yang and Wan-Chun Tang contributed equally to this work. a e-mail: [email protected] b e-mail: [email protected] (corresponding author)
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materials becomes very important. In optical frequency band range metals are similar to cold plasma and it can be expressed by dispersion model. Such as, Debye model, Drude model and Lorentz model [9–15]. In order to represent the properties of various materials more accurately, linear combinations of dispersion models are usual
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