Optimization of Purcell-enhanced microcavities with the cylindrical finite-difference time-domain algorithm

Quantum dots embedded in annular bullseye microcavities have been reported to be efficient single-photon sources. However, the proposed structures thus far often involve gratings of fixed periodicities, which may not be optimal considering the fact that Bessel functions are nonperiodic. In this paper, we present an optimization scheme for chirped annular microcavities where Purcell factors larger than 80 can be achieved through astute selection of the optimization function.