17 November 2010 Numerical study on radially polarized beam focusing through dielectric interface and metallic film
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Abstract
The strong lateral polarization component of radially polarized beam focused by high numerical aperture objective shows totally axis-symmetrical property, which gives rise to its widely applications in many optical devices. The equations of vectorial three dimensional(3D) electric field of radially polarized beam focused by high numerical aperture objective are given based on the vectorial Debye theory. The finite difference time domain(FDTD) method is applied to simulate the focusing of radially polarized beam. The electric field of radially polarized focal beam in a defocus plan calculated by Debye theory is induced as input source using the total/scatter field approach. We simulated the focusing processes in single dielectric medium and through the interface of two dielectric media, respectively. The distribution of electric field of the focus obtained from the FDTD results coincides with that directly calculated by Debye theory, which proves the facility of FDTD method for simulating the focusing optical field. Additionally, we simulate the focusing of radially polarized beam through dielectric half ball shaped nano-holes with different sizes. The focus shift effect caused by the different sizes of nano-holes provides the mechanism for changing the longitudinal position and the lateral resolution of the focus in subwavelength scale. At last, the surface plasmons excited by the radially polarized focus are shown at the surface of the metallic film and form a smaller focus. The simulation results of this paper will give contribution to the super-resolution focusing for nano-lithography.
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Xingyu Gao, Xingyu Gao, Lihua Ning, Lihua Ning, Xiaosong Gan, Xiaosong Gan, } "Numerical study on radially polarized beam focusing through dielectric interface and metallic film", Proc. SPIE 7848, Holography, Diffractive Optics, and Applications IV, 78481R (17 November 2010); doi: 10.1117/12.867984; https://doi.org/10.1117/12.867984
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