Multilayer Reconfigurable 3D Photonics Integrated Circuits Based on Deposition Method

Abstract Photonics integrated circuits (PICs) can overcome the bottlenecks in communication capacity. 3D PIC technology is an attractive method for increasing density effectively and combining different materials on one chip for functional integration. In this study, a low‐cost and reconfigurable 3D integrated silicon photonics (SiPhs) platform is proposed fabricated by depositing polycrystalline silicon (poly‐Si) on crystalline silicon (c‐Si), which is patterned through deep ultraviolet (DUV) stepper‐based manufacturing process. The high mobility of poly‐Si ensures high‐speed and power‐efficient modulation. Based on the proposed 3D SiPhs platform, an 8 × 8 optical switch whose units are separated in different layers is fabricated and packaged. The switch shows average insertion losses of −13.98 and −15.86 dB, while working in “all‐cross” and “all‐bar” states, respectively. The crosstalk is lower than −19 and −11 dB for “all‐cross” and “all‐bar” states. Additionally, an overlayer switch located on the 1st and 3rd layers is proposed and experimentally demonstrated, which offers overlapping capabilities that are more compact compared with switches in a single‐layer platform. This validates the possibility of the large‐density integration scalability of the platform.