Efficient Rational Approximation of Optical Response Functions with the AAA Algorithm

A theoretical framework for the rational approximation of optical response functions in resonant photonic systems is introduced. The framework is based on the AAA algorithm and further allows to solve the underlying nonlinear eigenproblems and to efficiently model sensitivities. An adaptive sampling strategy exploits the predominance of resonances in the physical response. A chiral metasurface is investigated and it is shown that the chiroptical response on parameter variations can be accurately modeled in the vicinity of the relevant resonance frequencies.