We report studies of material processing using the VUV F2 laser which, by virtue of its low threshold, high resolution 'machining' capability, may bring advantage to laser-based optoelectronic and photonic device fabrication. For example, probe beam deflection and etch rate studies of polymethylmethacrylate (PMMA) show this has a low ablation threshold, FT=20mJcm-2, and a large effective absorption coefficient, 1.6 x 105 cm-1, at 157nm, permitting high-resolution etching at modest fluence. The smooth ablated surfaces and low degree of thermal damage obtained with this laser make it well suited to machining structures such as relief gratings in PMMA. We also describe new results on producing fiber Bragg gratings with the 157nm laser. It is shown that these gratings can be written in a non-sensitized single mode fiber (Corning HI 980) with a low fluence and low total dose.
The 157nm F2 laser wavelength is strongly absorbed by glasses, even those with high silica content, making it potentially well suited for machining these materials by ablation. This is of interest for fabricating micro-optics and micro-devices in glass, provided crack-free surfaces with minimal laser-induced stress and surface roughness can be produced. Experimental studies are reported on the ablation threshold, ablation rate and surface quality of N-BK7 and soda lime glass for exposure with the VUV F2 laser. Optical probe techniques and etching are employed to determine the ablation threshold and removal rate and scanning electron microscopy to assess the surface quality of the glass following laser exposure. The interaction is discussed within the framework of a thermal vaporization model and the surface thermal loading is used to make a preliminary assessment of resolution attainable in micro-feature definition.
Theoretical and experimental studies of the surface quality in 157 nm F2 laser-ablated glasses are reported. Limitations set by statistical fluctuations in the multi- mode beam and by stationary beam non-uniformity are explored together with materials issues such as laser-induced surface cracking. Experimental work on ablating polymethyl methacrylate, used as a low threshold medium for recording of the VUV beam, and soda lime glass are described. Use is made of the probe beam deflection technique to determine ablation thresholds, and a variety of methods adopted for characterizing and assessing the quality of ablated surfaces e.g. scanning-electron microscopy, mechanical and optical interference profiling and atomic force microscopy. Preliminary roughness measurements are compared with theoretical expectations and the implication for glass micromachining with the F2 laser discussed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.