Back‐End‐Of‐Line Integrated Non‐Volatile Reconfigurable Devices for Programmable Photonic Integrated Circuits

ABSTRACT Chalcogenide phase change materials (PCMs) integrated photonics is characterized by zero static power consumption and compact footprint, offering a breakthrough tuning method for large‐scale programmable photonic integrated circuits (PICs). To facilitate the development of large‐scale PCMs‐based PICs, the performance requirements of units in non‐volatile PICs for specific applications are analyzed, and back‐end‐of‐line (BEOL) integrated non‐volatile devices with enhanced performance are proposed. First, loss reduction is proven to benefit reconfigurable filtering to a significant degree. With the integration of Sb 2 Se 3 , a low‐loss (0.38 dB π −1 ) phase shifter with high phase modulation efficiency (0.135π µm −1 ) is realized. Meanwhile, the participation of wide‐range attenuations enables more versatile programming, a Ge 2 Sb 2 Se 4 Te 1 ‐based attenuator is developed, achieving high switching endurance (>10 000 cycles) with a large extinction ratio (>40 dB). Second, a non‐volatile 2 × 2 Mach–Zehnder interferometer (MZI) is proposed, since lower switch crosstalk (<−20 dB) enables improved encoding performance with reduced bit error rates (BER). Finally, sufficient multilevel precision is crucial for optical computing because of the direct association between mapping errors and prediction accuracy. Accordingly, an add‐drop microring resonator (MRR) is fabricated, achieving a multilevel precision of 44 levels. This study presents an essential step to scaling up PCMs‐based PICs for diverse photonic applications.