Heptad Phase Vortex Array in Extremely Deep Fresnel Diffraction Region Generated by Asymmetrical Metal Subwavelength Holes Film

• 来源期刊: 中国物理快报（英文版）
• 关键词: @@
• 年，卷（期）: 2015,（10）
• 页码范围: 63-67
• 页数: 5页
• 语种: 中文
• DOI: 10.1088/0256-307X/32/10/104209

摘要

We report a heptad vortex array structure in the wave fields in an extremely deep Fresnel diffraction region by asymmetrical subwavelength holes in a metal film illuminated with linearly polarized light.A Mach-Zehnder interferometer with a microscopic objective is used to record the wave fields at different distances,and the phase maps are extracted by Fourier transform of the interference intensities.We study the evolutions of the heptad vortex array with distance from the sample to the object plane.To explain the formations and the evolutions of the vortex array,we calculate the diffracted wave fields with Kirchhoff's diffraction theory.The calculations are basically consistent with the experimental results,and the properties of the heptad vortex array structure are reasonably explained.