Fabrication-constrained nanophotonic inverse design

Abstract

A major difficulty in applying computational design methods to nanophotonic devices is ensuring that the resulting designs are fabricable. Here, we describe a general inverse design algorithm for nanophotonic devices that directly incorporates fabrication constraints. To demonstrate the capabilities of our method, we designed a spatial-mode demultiplexer, wavelength demultiplexer, and directional coupler. We also designed and experimentally demonstrated a compact, broadband $1\times 3$ power splitter on a silicon photonics platform. The splitter has a footprint of only $3.8\times 2.5\hat{\mathrm{I}}¼\mathrm{m}$, and is well within the design rules of a typical silicon photonics process, with a minimum radius of curvature of $100\mathrm{nm}$. Averaged over the designed wavelength range of $1400-1700\mathrm{nm}$, our splitter has a measured insertion loss of $0.642\pm 0.057\mathrm{dB}$ and power uniformity of $0.641\pm 0.054\mathrm{dB}$.

13 pages, 8 figures