An optical disc is constructed for operation in an alloying mode and includes first recording sublayer of Ge-Sb-Te and a second recording sublayer of Bi-Te. Apparatus is provided for recording information at a predetermined power level on an optical disc in the alloying mode or phase transformation mode in accordance with disc-type information associated with the disc or cartridge and readable by the apparatus. There is also provided an environmental aging technique for use in constructing optical discs to obviate significant dimensional changes in the discs during use between the extremes of the operating environment. There is further provided an optical disc construction and method in which an inorganic dielectric deposited on an organic substrate includes a hydrocarbon. There is additionally provided an optical disc construction and method in which a plasma polymer layer is disposed between an inorganic dielectric layer over the recording layer and a resin layer.
