Self-Developing, Ultrafast Holographic Materials
Original Publication Date: 1988-Apr-01
Included in the Prior Art Database: 2005-Feb-15
Amorphous films of the chalcogenide semiconductor compound GeTe were utilized to obtain ultrafast holographic recording with a commercial excimer laser providing 12 ns long pulses at 248 nm. Single laser pulses were utilized. The net reflectivity changes after laser exposure. The reflectivity change is due to material crystallization and indicates that a critical fluence-threshold must be exceeded for this process to occur. At very high fluences, a single laser pulse suffices to fully crystallize the film at least to a thickness comparable to the skin depth of the probe laser. In the intermediate regime of 19 to 24 mJ/cm, for the case of this 200 nm thick film, several laser pulses must be applied to obtain the degree of crystallization observed when using very high laser fluences.