Efficient sensitivity analysis of photonic structures with transmission line modeling

We introduce a memory efficient approach for the reduction of the required memory storage in time domain transmission line modeling (TLM)-based adjoint variable method (AVM). The proposed approach is based on manipulating the TLM scattering matrices to remove all redundant calculations. The required memory overhead for our approach is drastically reduced to only 10% of that of the original TLM-based AVM. This represents the ultimate memory reduction preserving the same accuracy of previously reported AVM approaches. Utilizing this approach, we can conduct AVM calculations for dielectric bulk structures 10 times larger. Our algorithm has been verified by comparison to the expensive finite difference approaches.