Laser processing of sapphire with picosecond and sub-picosecond pulses

D. Ashkenasi, A. Rosenfeld, H. Varel, M. Wähmer, E. E.B. Campbell

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238 Scopus citations

Abstract

Laser processing of sapphire using a Ti:sapphire laser at 790 and 395 nm and pulse widths varying between 0.2 and 5 ps is reported. A clear improvement in quality is demonstrated for multi-shot processing with sub-ps laser pulses. For fluences between 3 and 12 J/cm 2 two ablation phases were observed, in agreement with previous work from Tam et al. using 30 ps, 266 nm laser pulses [A.C. Tam, J.L. Brand, D.C. Cheng, W. Zapka, Appl. Phys. Lett. 55 (20) (1994) 2045]. During the 'gentle ablation' phase periodic wavelike structures, i.e. ripples, were observed on the Al 2 O 3 surface, perpendicular to the laser polarisation and with a spacing almost equalling the laser wavelength, indicating metallic-like behaviour. The ripple modulation depth was in the order of a few tens of nm. For fluences between 1 and 2.5 J/cm 2 , below the single-shot surface damage threshold and at a pulse width above 200 fs, microstructures could be produced at the rear side of a 1 mm thick sapphire substrate without affecting the front surface.

Original languageEnglish
Pages (from-to)65-80
Number of pages16
JournalApplied Surface Science
Volume120
Issue number1-2
DOIs
StatePublished - Nov 1997

Bibliographical note

Funding Information:
We would like to thank Dr. R. Kelly, Dr. E. Kotomin and Dr. J. Herrmann for useful discussions and Dr. F. Noack and G. Mügge for help in carrying out the experiments. Financial support from the BMBF (13N6591, PROBE) is gratefully acknowledged.

Keywords

  • Sapphire
  • Ultrashort pulse laser ablation

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