Ultrafast reversible phase change in GeSb films for erasable optical storage

Amorphous-to-crystalline and crystalline-to-amorphous transformations are triggered in GeSb thin films by irradiation with femtosecond and picosecond laser pulses. Phase changes are accompanied with optical contrast and therefore the feasibility of phase-change optical recording at ultrafast rates is demonstrated for the first time. The phase reversal by ultrashort pulses seems to be related to the dependence of the degree of undercooling prior to solidification on the irradiation energy density.