Time-resolved reversible optical switching of the ultralow-loss phase change material Sb2Se3

TL;DR

This study explores the ultrafast optical switching dynamics of Sb2Se3, revealing nanosecond vitrification and millisecond crystallization processes, which are crucial for optimizing photonic phase change devices.

Contribution

It provides the first detailed time-resolved analysis of Sb2Se3's phase change dynamics under optical excitation, highlighting the large difference in vitrification and crystallization times.

Findings

Vitrification occurs in nanoseconds.

Crystallization occurs in milliseconds.

Large five-orders of magnitude difference in time scales.

Abstract

The antimony-based chalcogenide Sb2Se3 is a rapidly emerging material for photonic phase change applications owing to its ultra-low optical losses at telecommunication wavelengths in both crystalline and amorphous phases. Here, we investigate the dynamical response of these materials from nanoseconds to milliseconds under optical pumping conditions. We apply bichromatic pump-probe transient reflectance spectroscopy which is a widely used method to study the optical performance of optical phase change materials. Amorphous regions of several hundreds of nanometers in diameter are induced by pulsed excitation of the material using a wavelength of 488 nm above the absorption edge, while the transient reflectance is probed using a continuous wave 980 nm laser, well below the absorption edge of the material. We find vitrification dynamics in the nanosecond range and observe crystallization on millisecond time scales. These results show a large five-orders of magnitude difference in time scales between crystallization and vitrification dynamics in this material. The insights provided in this work are fundamental for the optimisation of the material family and its employment in photonic applications.