Is optical storage a nonvolatile storage device or a volatile storage device?

It is nonvolatile, if you turn off the computer, the disc is not erased. (if you have a dvd bluray or cd and you turn off the cd, dvd, or bluray player the songs or movie on the disc is not erased). It does not use electrons to store data, it uses grooves and bumps in the disc and is read with a laser