We report the detailed analysis on the phase discontinuity, field distribution, penetration depth and photon lifetime in 1D and 2D PC mirrors. Compared to classical distributed Bragg reflectors (DBRs), these new types of PC mirrors exhibit different phase discontinuties and slower phase changes over the high reflection bands for surface-normal incident beams. Fabry-Perot (FP) cavity designs were carried out based on these three types of dielectric reflectors. In PC mirror based FP cavities, we observed penetration depth of 2~4μm, which is related to the large phase discontinuity. On the other hand, due to the tight field confinement, the energy penetration depths were ~ 0.1μm in PC mirror based FP cavities, much lower than that in DBR based FP cavities. We will also report on the distinctively different field distribution behaviors in these cavities, which are critical in the design of various active optoelectronic devices.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.