System of laser pump and synchrotron radiation probe microdiffraction to investigate optical recording process

Abstract

We have developed a system of laser-pump and synchrotron radiation probe microdiffraction to investigate the phase-change process on a nanosecond time scale of Ge2Sb2Te5 film embedded in multi-layer structures, which corresponds to real optical recording media. The measurements were achieved by combining (i) the pump-laser system with a pulse width of 300 ps, (ii) a highly brilliant focused microbeam with wide peak-energy width (ΔE∕E ~ 2%) made by focusing helical undulator radiation without monochromatization, and (iii) a precise sample rotation stage to make repetitive measurements. We successfully detected a very weak time-resolved diffraction signal by using this system from 100-nm-thick Ge2Sb2Te5 phase-change layers. This enabled us to find the dependence of the crystal-amorphous phase change process of the Ge2Sb2Te5 layers on laser power.

Phase‐Change Nanodot Material for an Optical Memory

“…Details of the setups are described in previous works. [18 , In the present experiment, changes in reflectivity from roughly 10 000 dots were observed in a group in one shot, where 100 shots of data (every shot was performed on virgin area of the sample) were accumulated to improve the signal to background ratio (S/B).…”