  In the past decades, silicon photonic integrated circuits (PICs) have been
considered as a promising approach to solve the bandwidth bottleneck in optical
communications and interconnections. Despite significant advances, large-scale
PICs still face a series of technical challenges, such as footprint, power
consumption, and routing state storage, 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
Ge2Sb2Te5 (GST) with silicon photonics, especially applicable in switching
applications due to the nonvolatile nature of the GST. Although GST phase
transitions between amorphous and crystalline states actuated by optical and
electrical pulses heating have been experimentally demonstrated, there is no
direct comparison between them. We carried out simulations and experiments to
systematically investigate the difference in the phase change process induced
by optical and electrical pulses for two types of Si-GST hybrid waveguides. For
the phase transition induced by optical pulses, the device has a clear
advantage in terms of power consumption and operation speed. For the phase
transition induced by electrical pulses, the device is suitable for large-scale
integration because it does not require complex light routing. It helps us
better understand the phase change process and push forward the further
development of Si-GST hybrid integration platform, bringing in new potential
applications.
