Seeded topology optimization for commercial foundry integrated photonics

We present a seeded topology optimization methodology for integrated photonic devices fabricated on foundry platforms that yields improved performance compared to traditional topology optimization. We employ blurring filters and a design rule check correction algorithm to more readily meet fabrication constraints, resulting in devices with fewer artifacts and improved correlation between simulation and measurements. A statistical study is performed on a 2D modal multiplexer, revealing that 87% of devices optimized using this strategy conform to foundry constraints, compared to 13% of devices optimized using traditional TO. We apply seeded topology optimization to an ultra-compact TE modal multiplexer, a TE mode converter, a polarization rotator, and a high-contrast grating reflector. Using this optimization strategy, the measured insertion loss of the TE mode converter was reduced from <1.50 to <0.64 dB, and the measured TE1 insertion loss of the TE modal multiplexer was reduced from <3.95 to <1.38 dB over C-band. This approach enables a two-step inverse design process, merges physics-informed design strategies with inverse design, and ensures strict compliance with foundry constraints throughout optimization.