Femtosecond-laser-assisted high-aspect-ratio nanolithography in lithium niobate

• Published in: Nanoscale 2023-09, Vol.15 (37), p.15298-1533
• Main Authors: Wang, Tianxin, Cheng, Xiaoyan, Li, Xuan, Ma, Jianan, Yan, Shuo, Hu, Xueli, Qi, Kai, Fan, Weiwen, Liu, Manman, Xu, Xiaoyi, Lu, Xiaomei, Jiang, Xiaoshun, Zhang, Yong
• Format: Article
• Language: English
• Subjects: Arrays; Chemical etching; High aspect ratio; Lasers; Lithium niobates; Nanolithography
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/d3nr03750a

We report the successful fabrication of high-aspect-ratio lithium niobate (LN) nanostructures by using femtosecond-laser-assisted chemical etching. In this technique, a 1 kHz femtosecond laser is first used to induce local modifications inside the LN crystal. Then, selective chemical wet etching is conducted using a buffered oxide etch (BOE) solution. The etching rate in the laser-modified area reaches 2 μm h −1 , which is enhanced by a factor of ∼660 in comparison to previous reports without laser irradiation. Such high selectivity in chemical etching helps realize high-performance maskless nanolithography in lithium niobate. In the experiment, we have fabricated high-quality LN nanohole arrays. The nanohole size reaches ∼100 nm and its aspect ratio is above 40 : 1. The minimal period of the LN hole array is 300 nm. Our work paves a way to fabricate LN nano-integrated devices for advanced optic and electronic applications. A femtosecond-laser-assisted lithium niobate nanolithography technique is developed. The etching rate is enhanced to 2 μm h −1 . The nanohole size reaches ∼100 nm and the aspect ratio is above 40 : 1.