Binary Two-Phase Gratings Formed on the Surface of Ge₂Sb₂Te₅ Thin Film by Femtosecond Laser Pulses

The formation of binary amorphous-crystalline periodic structures on the surface of Ge2Sb2 Te5 thin film during a single pass of a femtosecond laser beam has been studied. We recorded biphase stripes up to several mm long consisted of 50 parallel amorphous/crystalline lines oriented perpendicular to the light polarization. These stripes had a period equal to the recording beam wavelength (1030 nm) and exhibited diffraction grating behavior due to the remarkable optical contrast. We performed diffraction simulations and obtained good agreement with the experimental results for a beam (532 nm) diffracted by the recorded grating.