Design of robust and efficient photonic switches using topology optimization

► We provide a methodology for designing nonlinear optical devices. ► The devices’ performance is robust with respect to manufacturing uncertainties. ► The topology variations are incorporated in the optimization algorithm. ► The robust approach can be applied to designs containing three and more materials. ► The optimization procedure is applied for time domain problems. The aim of this article is to introduce a systematic approach for design of non-linear optical devices. The designs are obtained using gradient-based topology optimization coupled with a time-domain Maxwell's equations solver. Direct application of the optimization procedure results in devices with a performance which is very sensitive to geometric manufacturing errors (under- or over-etching). Such behavior is undesirable and robustness is achieved by optimizing for several design realizations. The possible geometric uncertainties are modeled by random variables. It is shown that the designs are insensitive with respect to variations of signal parameters, such as signal amplitudes and phase shifts. The obtained robust designs of a 1D photonic switch can substantially outperform simple bandgap designs, known from the literature, where switching takes place due to the bandgap shift produced by a strong control pulse.