Ultrahigh Endurance and Extinction Ratio in Programmable Silicon Photonics Based on a Phase Change Material with ITO Heater

Phase-change-materials (PCMs) integrated photonics have attracted extensive attention in the field of optical neural networks. However, present PCMs-integrated photonics are still far from meeting the requirements in real-world applications due to its unsatisfactory endurance (<3000 cycles) and extinction ratio (ER<20 dB). Here, ultrahigh endurance (>30 000 cycles) and large ER (>= 50 dB) are achieved in the photonic device by introducing a trench structure to the indium tin oxide (ITO) heater and utilizing tin-doped Ge2Sb2Te5 (Sn-GST) as PCMs. This performance represents a landmark in the PCMs-integrated photonics, since it solves the problem of poor endurance of ITO heaters and can be comparable to the state-of the-art devices in terms of endurance and ER. This excellent endurance and ER stem from the trench structure and high optical contrast PCM of Sn-GST. Trench structure improves the heating efficiency of the ITO heater and effectively alleviates the thermal stress imposed on the ITO heater, resulting in ultrahigh endurance of the device. Sn-doping is also beneficial to the endurance and ER improvement, because it can effectively reduce the crystallization temperature and increase the absorption coefficient of the PCM layer. This work provides a new technology for the development of programmable photonics with ultrahigh endurance.