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

Abstract

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.

Deterministic quasi-continuous tuning of phase-change material integrated on a high-volume 300-mm silicon photonics platform

“…Recent years has indeed witnessed significant advancements in PCMbased programmable PICs, controlled by short laser or electrical pulses for applications such as optical memories 31,32 , programmable optical switches 20,21,23,24,[33][34][35][36] , low-power in-memory computing 10,14,37,38 and optical trimming 22,24 . Compared to the optical actuation scheme 10,14,31,33,39 , the electrically controlled methods 20,21,23,24,26,35,36 eliminate the requirements for sophisticated and bulky pulsed laser setups. Therefore, they are more promising for a faster and more accessible real-time control, enabling true integration of the entire optical systems on a chip.…”

“…S11) shows some black areas at the edge of waveguides after the cyclability test, which could be a result of Sb 2 S 3 ablation or thermal reflowing. Several strategies can be used to further improve the cyclability, such as developing more endurable PCMs 35 , engineering the thickness and material of the encapsulation layer 48 , patterning the PCMs into subwavelength nanostructures 49 , and engineering the microheaters and pulse conditions to provide a uniform temperature distribution 44 .…”