A new optical information storage technique is described which operates by irreversibly altering the absorption properties of a microscopically textured surface. Reflectance changes of greater than a factor of 100 have been obtained by local melting of the surface. A random array of Si columns with cross-sectional dimensions less than 100 nm, formed on a Si film by reactive ion etching, has a visible reflectance of less than 0.01. By irradiation with a focused laser beam, at a power density of ≲8 mW/μm2, the columns melt to form a surface with a specular reflectance of ∼0.4. The applicability of this surface structure as a permanent optical storage medium is discussed. In general, this surface texturing can be applied to a wide variety of materials with the advantages of increased sensitivity to the writing beam, large contrast between the written and unwritten areas and reduced lateral energy flow.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)