Comparison of the phase change process in a GST-loaded silicon waveguide and MMI.

In the past decades, silicon photonic integrated circuits (PICs) have been considered a promising approach to solve the bandwidth bottleneck in optical communications and interconnections. Despite the rapid advances, large-scale PICs still face a series of technical challenges, such as large footprint, high power consumption, and lack of optical memory, resulting from the active tuning methods used to control the optical waves. These challenges can be partially addressed by combining chalcogenide phase change materials (PCMs) such as GeSbTe (GST) with silicon photonics, especially applicable in reconfigurable optical circuit applications due to the nonvolatile nature of the GST. We systematically investigate the phase change process induced by optical and electrical pulses in GST-loaded silicon waveguide and multimode interferometer. Using optical pulse excitation to amorphize GST has a clear advantage in terms of operation speed and energy efficiency, while electrical pulse excitation is more suitable for large-scale integration because it does not require complex optical routing. This study helps us better understand the phase change process and push forward the further development of the Si-GST hybrid photonic integration platform, bringing in new potential applications.