基于聚合物低单光子吸收连续激光直写技术研制亚衍射极限纳米孔阵列

Direct CW-laser writing sub-diffraction-limit nanopore array based on the low one-photon absorption of polymer

摘要:

基于单光子吸收激光直写技术,成功地制备了大面积阵列分布、一致性可控的纳米孔复合结构。通过一种涡旋相位板的调制,532nm波段的连续激光在高数值孔径物镜的焦点处形成了一个圆环形光斑,作用于均匀的SU8光刻胶薄膜上,进而制备出形状与大小可控的、具有高深宽比、直径突破阿贝衍射极限的纳米孔结构。通过逐点扫描方法,最终制备出内径仅为入射波长~1/10的纳米孔阵列结构。此外,利用SEM技术研究了曝光光强和曝光时间对纳米孔尺寸和形貌的影响。

Abstract:

A large area nanopore array with controllable consistency has been successfully fabricated by direct laser writing (DLW) technique with ultralow one-photon absorption (LOPA). In this technique, a doughnut-shape beam generated by 532 nm continuous-wave laser through a vortex phase plate is focused into the thin film of SU8 photoresist by a high numerical aperture objective. The low absorption of the photoresist at the excitation wavelength allows controllable fabricating structures with sub-diffraction-limit feature size and high aspect ratio. With point-by-point scanning fabrication, nanopore array with the pore’s internal diameter, about ten per cent of incident laser wavelength, far smaller than Abbe’s diffraction limit is achieved. The influences of the exposure intensity and exposure time on the fabricated nanopore size and shape are also investigated by scanning electron microscope (SEM).