Towards optical quality micro-optic fabrication by direct laser writing and chemical etching

Calum Ross, David Guillaume MacLachlan, Debaditya Choudhury, Robert R. Thomson

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Citations (Scopus)


Here we demonstrate the use of an advanced microfabrication technique, known as ultrafast laser inscription (ULI) with chemical etching, optimised for the fabrication of micro-optic systems in fused silica. ULI is a precision laser micromachining tool which relies on the high peak intensities associated with focused femtosecond pulses of light to locally modify the structure of a dielectric material. One manifestation of this modification is that the etch-rate of the modified regions can be increased by up to two orders of magnitude compared to that of pristine material, depending on the specific ULI parameters and the chemical etchant used. This capability means that ULI facilitates the repeatable fabrication of three-dimensional freeform structures in glass with micrometre resolution. Firstly, we present the results of investigations aimed at optimising the fabrication process and show that by controlling the laser polarisation during inscription, an etch-rate selectivity of 100 and a fivefold decrease in surface roughness can be achieved. We then demonstrate the characterisation of a microlens fabricated with optimum inscription parameters, including measurements of the lens surface profile, surface roughness and throughput, before demonstrating that the local surface roughness can be further decreased to below 5 nanometres by post-manufacture flame polishing.

Original languageEnglish
Title of host publicationFrontiers in Ultrafast Optics
Subtitle of host publicationBiomedical, Scientific, and Industrial Applications XVII
ISBN (Electronic)9781510606296
Publication statusPublished - 17 Feb 2017

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


  • Chemical etching
  • Femtosecond micromachining
  • Flame polishing
  • Microoptic fabrication
  • ULI
  • Ultrafast laser inscription

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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