phase change mode

The phase-change process is a recording process in optical storage used in rewritable DVDs,Blu-Raydiscs( BD-RE) and 3D XPoint storage. The phase-change process is based on the intensity control of a laser that heats the complex storage layers of the optical recording discs in several phases.

In the case of DVD and Blu-Ray optical storage media, the recordable storage layer consists of a transparent multilayer substrate layer with a recording layer behind it. During the writing process, the recording layer is converted into a crystalline state or, at higher temperatures, into an amorphous state by spot heating. Only the crystalline structure reflects the laser light. The phase-change process, in which the laser power and thus the light energy is controlled, creates a sequence of reflective and non-reflective zones on the substrate.

An electrical phase-change process is also usedin memory technology, namely in phase-change memory. In this process, heat is used to change the material structure between crystalline and amorphous.