Multi-bit subnanocesond optical switching of GST225 for photonic memory and computing

Abstract

In this work, we demonstrate stable multi-bit (discrete) modulations of the optical properties of thin-film GST₂₂₅ (Ge₂Sb₂Te₅ or GST) samples as a result of phase transitions induced by femtosecond (≈ 50 fs) laser pulses. An ultra-high crystallization rate of the SET material is shown, ~13 m/s. One- and many-step modulations of optical properties are obtained during crystallization of the sample material. Reamorphization or RESET of the samples occurs at a rate of 5–6 m/s; it is realized in several impacting pulses. This fact indicates the thermal nature of the phase transitions.