Yu Yuh-Yan, Lin Ding-Zheng, Huang Long-Sun, Lee Chih-Kung
Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan.
Opt Express. 2009 Feb 16;17(4):2707-13. doi: 10.1364/oe.17.002707.
A subwavelength annular aperture (SAA) made on metallic film and deposited on a glass substrate was fabricated by electron-beam lithography (EBL) and which was followed by a metal lift-off process to generate a long propagation range Bessel beam. We propose tuning the focal length and depth of focus (DOF) by changing the diameter of the SAA. We used finite-difference time domain (FDTD) simulations to verify our experimental data. We found that the position of the Bessel Beam focus spot (i.e. focal length) will be farther away from the SAA plane as the diameter of the SAA increases. In addition, the depth of focus (DOF) which is the length of the Bessel beam non-diffracting area, also increases as the diameter of the SAA expands.
通过电子束光刻（EBL）在金属薄膜上制作一个亚波长环形孔径（SAA），该金属薄膜沉积在玻璃基板上，随后进行金属剥离工艺以产生长传播范围的贝塞尔光束。我们提出通过改变SAA的直径来调整焦距和焦深（DOF）。我们使用时域有限差分（FDTD）模拟来验证我们的实验数据。我们发现，随着SAA直径的增加，贝塞尔光束焦点的位置（即焦距）将远离SAA平面。此外，作为贝塞尔光束非衍射区域长度的焦深（DOF）也随着SAA直径的扩大而增加。
