The Blu-Ray disc BD-RE - RE stands for Rewritable - is a rewritable Blu-Ray disc that is written using the phase change process. Blu-Ray discs consist of several layers.
There is the single layer, Single Layer (SL), and the dual layer, Dual Layer (DL). A single layer BD-RE consists of seven superimposed layers, a dual layer of eleven layers.
The innermost layer is the carrier layer, on top of which is a reflective layer with a dielectric layer. Only then comes the rewritable layer, on which again a dielectric layer, the cover layer and the protective layer are applied. The rewritable layer consists of a germanium or indium-antimony alloy that reacts to different light intensities. By beam modulation of the laser beam, data can be written and erased in the pre-made grooves in the different layers. The outer protective layer protects the BD-RE against deterioration due to dirt and fingerprints.GB, 25 GB and 27 GB in the single layer (SL) version, and twice as high in the dual layer (DL) version with 46.6 GB, 50 GB and 54 GB. In addition to the standard size with a diameter of 120 mm, there is also a smaller format with a diameter of 80 mm.