High-aspect-ratio, high-quality microdrilling by electron density control using a femtosecond laser Bessel beam

Qian Xie, Xiaowei Li, Lan Jiang, Bo Xia, Xueliang Yan, Weiwei Zhao, Yongfeng Lu

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Abstract

We propose an efficient microdrilling method of high-aspect-ratio, high-quality microholes in polymethyl methacrylate by controlling localized transient spatial electron density using single-pulse femtosecond laser Bessel beams. The microholes fabricated with diameters of 1.5–2.4 μm are taper-free, which are of much better quality in the entrances and sidewalls, as compared with those fabricated by Gaussian beams. The aspect ratio of the microholes is up to 330:1. It takes 42 min to fabricate a 501 × 501 microhole array (with 251,001 holes in total, about 100 holes per second under a repetition rate of 100 Hz) in a 1 cm × 1 cm area, which is very uniform in size and shape. For single-pulse drilling of a microhole array, the number of ultrahigh-aspect-ratio microholes processed per second is theoretically determined by the repetition rate. The liquid infiltration method and cross-sectional profile tests confirm hollow microhole drillings rather than material modifications. The theoretical simulation of optical intensity distribution and intensified charge-coupled device detection shows that fabricating such thin, long, uniform microholes using Bessel beams is attributed to electron density control by spatially shaping femtosecond laser pulses.

Original languageEnglish (US)
Article number136
Pages (from-to)1-8
Number of pages8
JournalApplied Physics A: Materials Science and Processing
Volume122
Issue number2
DOIs
StatePublished - Feb 1 2016

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ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)

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