Patent ID: 6985373
Filing Date: 2006-01-10
Classification: G02F

Abstract:
1. An element for directing an incident electromagnetic beam comprising a first dielectric layer; an active layer formed on said first dielectric layer, said active layer comprising a plurality of phase change regions, said phase change regions comprising a phase change material, said phase change material having a first crystallographic form and a second crystallographic form, said phase change regions having a plurality of structural states, each of said structural states including a first proportion of said first crystallographic form and a second proportion of said second crystallographic form; and a second dielectric layer formed on said active layer; said phase change regions having a first phase angle state and a second phase angle state, said phase change regions providing a first interval of phase angles when in said first phase angle state and a second interval of phase angles when in said second phase angle state, said first phase angle state including a first subset of said structural states spanning a first range of proportions of said first crystallographic form, said second phase angle state including a second subset of said structural states spanning a second range of proportions of said first crystallographic form, said first and second ranges of said proportions of said first crystallographic form being non-overlapping; wherein the structural state of said first phase angle state having the maximum proportion of said first crystallographic form and the structural state of said second phase angle state having the minimum proportion of said first crystallographic form differ in the proportion of said first crystallographic form by less than or equal to 20% and the phase angle of said maximum proportion of said first crystallographic form state of said first phase angle state and the phase angle of said minimum proportion of said first crystallographic form state of said second phase angle state differ by at least 45°.