  The complexity of applications addressed with photonic integrated circuits is
steadily rising and poses increasingly challenging demands on individual
component functionality, performance and footprint. Inverse design methods have
recently shown great promise to address these demands using fully automated
design procedures that enable access to non-intuitive device layouts beyond
conventional nanophotonic design concepts. Here we present a dynamic
binarization method for the objective-first algorithm that lies at the core of
the currently most successful inverse design algorithms. Our results
demonstrate significant performance advantages over previous implementations of
objective first algorithms, which we show for a fundamental TE00 to TE20
waveguide mode converter both in simulation and in experiments with fabricated
devices.
