Abstract

The size and the shape of micropores in anodic alumina films are studied by electron microscope observation and mercury intrusion porosimetry. Pores have conical shapes with ~10-nm diameters and are widened at the rate of ~0.05 nm/min by immersion in a sulfuric acid solution. Such conical pores give rise to the refractive-index distribution and anisotropy in the alumina films. By analyzing interference fringes, we find that a graded-index profile, as well as birefringence, exists in the anodic alumina films. The experimental results are in good agreement with theoretical predictions.

© 1993 Optical Society of America

Optical loss distribution in anodically oxidized alumina with a 2-D structure

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