Finite-element analysis in time and frequency domains using perfectly matched layers and isoparametric curvilinear elements for finite-size photonic-crystal (PC) cavities is presented in this paper. The time-domain approach includes current sources, the full band scheme, and the slowly varying envelope approximation; consequently, bigger time steps can be used independent of the size of the elements. The resonant frequency, quality factor, effective modal area, and field distribution for each mode can be obtained in a single simulation. A strategy to compute the higher resonant modes by using only a quarter of the cavity and adequate boundary conditions is also presented. © 2005 IEEE.