Fabrication-aware inverse design with shape optimization for photonic integrated circuits

Inverse design (ID) is a computational method that systematically explores a design space to find optimal device geometries based on specific performance criteria. In silicon photonics, ID often generates design features that degrade significantly due to the fabrication process, limiting the applicability of these devices in scalable fabrication. We demonstrate a solution to this performance degradation through fabrication-aware inverse design (FAID), integrating lithography models for deep-ultraviolet (DUV) lithography and electron-beam lithography (EBL) into the shape optimization approach of ID. A Y-branch and a subwavelength grating (SWG)-to-strip converter were generated and fabricated with this new, to the best of our knowledge, approach. Simulation and measurement results verify that FAID yields devices with up to 0.7 dB lower insertion loss per device. The modified workflow enables designers to use ID to generate devices that adjust for process bias predicted by lithography models.