Functionalization of freeform curved surfaces by shaped femtosecond laser pulses in the propagation axis

ANDONG WANG, LAN JIANG, XIAOWEI LI*, JI HUANG, ZHIJIE XU, ZHIPENG WANG, ZHULIN YAO

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

With ultrashort pulse durations and ultrahigh peak intensities, ultrafast lasers can create different types of micro/nano-structures to functionalize the processed surface with new properties. However, the applications of this method on freeform surfaces are still limited by the short length of a laser focusing spot and complex control of the 3D moving trajectory in the fabrication process. In this paper, we overcome this problem by shaping the on-axis intensity along the propagation axis using the spatial light modulator. By designing the phase mask, we increased the length of the stable-intensity zone (intensity fluctuation < 10%) by more than 3 times compared to that of an unshaped Bessel beam. The energy deposition was also optimized to be less than 2% fluctuation based on simulations. Using this method, we fabricated micro/nano structures on 3D surfaces at different fluences and demonstrated various properties including colorization, anti-reflection, and hydrophobicity in large height range. We demonstrated the applications of the proposed method in creating hydrophobicity on complex freeform syringe tip surfaces. This improved the minimum manipulatable volume of a liquid droplet to 2 times smaller compared with untreated syringe, thus greatly extending its performance for micro-droplet manipulation. This method offers an alternative approach for reliable and affordable freeform curved-surface processing.

Original languageEnglish
Pages (from-to)5487-5496
Number of pages10
JournalOptics Express
Volume29
Issue number4
DOIs
Publication statusPublished - 15 Feb 2021

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