Ultrafast Inverse Design of Electromagnetic Devices

This paper introduces the Precomputed Numerical Green Function (PNGF) method, a new approach for rapid inverse design of electromagnetic devices. The static components of the design are incorporated into a numerical Green function obtained from a single fully parallelized precomputation step, reducing the cost of evaluating candidate designs during optimization to only being proportional to the size of the region under modification. When used with the direct binary search optimization algorithm, a low-rank update technique is leveraged to further decrease the iteration time to seconds without approximations or compromises in accuracy. The total runtime for an inverse design is reduced by several orders of magnitude compared to using conventional Maxwell solvers due to the linear time complexity of the method, attaining speedups of up to 700x for the design examples considered and lowering the process from multiple days to weeks down to less than an hour. The performance and flexibility of the approach are highlighted with design studies, including experimental results, on an ultrawideband 30GHz substrate antenna with 50% fractional bandwidth, a 6GHz switched beam antenna steerable between angles 90{\deg} apart, and a broadband, ultra-short-length microstrip to substrate-integrated waveguide transition. The approach stands to reshape inverse design in electromagnetics.