(Peer-Reviewed) Microsphere femtosecond laser sub-50 nm structuring in far field via non-linear absorption
Zhenyuan Lin 林真源 ¹ ³, Kuan Liu 刘宽 ², Tun Cao 曹暾 ², Minghui Hong 洪明辉 ¹ ³
¹ Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University , Xiamen 361102, China
中国 厦门 厦门大学萨本栋微米纳米科学技术研究院
² School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, China
中国 大连 大连理工大学光电工程与仪器科学学院
³ Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore
Creation of arbitrary features with high resolution is critically important in the fabrication of nano-optoelectronic devices. Here, sub-50 nm surface structuring is achieved directly on Sb2S3 thin films via microsphere femtosecond laser irradiation in far field.
By varying laser fluence and scanning speed, nano-feature sizes can be flexibly tuned. Such small patterns are attributed to the co-effect of microsphere focusing, two-photons absorption, top threshold effect, and high-repetition-rate femtosecond laser-induced incubation effect.
The minimum feature size can be reduced down to ~30 nm (λ/26) by manipulating film thickness. The fitting analysis between the ablation width and depth predicts that the feature size can be down to ~15 nm at the film thickness of ~10 nm. A nano-grating is fabricated, which demonstrates desirable beam diffraction performance.
This nano-scale resolution would be highly attractive for next-generation laser nano-lithography in far field and in ambient air.