The writing process: CD-R
Digital information is written to the disc by burning (forming) pits in the recording layer.The energy of the laser beam - in the range 4 to 11 mW - causes limited heating of the substrate and recording layer to approximately 250°C. At this temperature the recording layer melts, reducing its volume, while the substrate expands into the space that becomes available. By constant switching between writing and reading power, a pit pattern corresponding to that of a conventional CD is produced.
The write pulse initially has a higher power to produce the required heating of the dye. Subsequently, the power is reduced to a level that is sufficient to maintain the dye
temperature at the desired level.