Model dispersive media in finite-difference time-domain method with complex-conjugate pole-residue pairs

In this letter, we show that both Debye poles and Lorentz pole pairs are special cases of complex-conjugate pole-residue pairs, and the general form of such pairs is in fact far more efficient than the commonly used Debye poles and Lorentz pole pairs for modeling real dispersive media with the finite-difference time-domain method. We first derive an alternative formulation of the auxiliary differential equation method for arbitrary dispersive media based on general complex-conjugate pole-residue pairs. We then numerically demonstrate the efficiency of using these pairs in modeling dispersive media.