CD-R Recording and Playback Principle
To record on a CD-R disc, a laser beam which has the same wavelength (780nm) but more than ten times the intensity strength as the CD beam, is used. This laser beam is spotted onto the substrate side of the disc and is focused into the groove.Then, the recording layer of organic dye absorbs the beam's energy and converts it into heat reaching 300°C inside the groove. This temperature rise causes the plastic substrate to deform and the dye to decompose, resulting in a change of the refractive index. This, in turn, causes optical interference conditions to change, forming a recorded mark.