Method of changing reflectance or resistance of a region in an optoelectronic memory device

A method for changing reflectance of a region in an optoelectronic memory device, said method comprising:

• sending an electric current through the region so as to cause a change in a reflectance of the region from a first value of reflectance to a second value of reflectance different from the first value of reflectance, said region comprising a material;
• and
• optically reading the change in the reflectance of the region,
• wherein said optically reading the change in the reflectance of the region comprises:
• sending a first incident laser beam to the region;
• receiving a first reflected beam from the region, wherein the first reflected beam is a result of a reflection of the first incident laser beam off the region;
• sending a second incident laser beam to another reference region, wherein the another reference region is essentially identical to the region;
• receiving a second reflected beam from the another reference region wherein the second reflected beam is a result of a reflection of the second incident laser beam off the another reference region;
• and
• comparing beam intensities of the first and second reflected beams.

A method for changing reflectance of a region in an optoelectronic memory device, said method comprising:

• sending an electric current through the region so as to cause a change in a reflectance of the region from a first value of reflectance to a second value of reflectance different from the first value of reflectance, said region comprising a material;
• and
• optically reading the change in the reflectance of the region,
• wherein the change in the reflectance of the region is due to a phase change in the material.