| 摘要 |
<p>A method of optical data storage uses photo-induced dispersion change (PIDC) material -such as a photochromic fulgide- which is reversibly transformable upon absorption of radiation at a wavelength μw to a thermally stable, changed form of a different refractive index. Writing is conducted at a wavelength μw to transform the PIDC material in localised regions to the changed form to produce a difference in refractive index δn between each region and the PIDC material immediately surrounding. Reading is carried out at a wavelength μr through a path length L of the PIDC material, with δn and L being selected such that there is a phase difference of substantially nμr/2 between radiation passing through a region and the PIDC immediately surrounding that region. Reading, writing and erasing can be conducted from one or both sides of the PIDC material which is conveniently provided on a substrate disc.</p> |
