Photon confinement in photonic crystal nanocavities

Abstract

Abstract The quest for enhanced light‐matter interactions has enabled a tremendous increase in the performance of photonic‐crystal nanoresonators in the past decade. State‐of‐the‐art nanocavities now offer mode lifetime in the nanosecond range with confinement volumes of a few hundredths of a cubic micrometer. These results are certainly a consequence of the rapid development of fabrication techniques and modeling tools at micro‐ and nanometric scales. For future applications and developments, it is necessary to deeply understand the intrinsic physical quantities that govern the photon confinement in these cavities. We present a review of the different physical mechanisms at work in the photon confinement of almost all modern PhC cavity constructs. The approach relies on a Fabry‐Perot picture and emphasizes three intrinsic quantities, the mirror reflectance, the mirror penetration depth and the defect‐mode group velocity, which are often hidden by global analysis relying on an a posteriori analysis of the calculated cavity mode. The discussion also includes nanoresonator constructs, such as the important micropillar cavity, for which some subtle scattering mechanisms significantly alter the Fabry‐Perot picture.