Design of photonic crystal microcavities in diamond films.

We design photonic crystal microcavities in diamond films for applications in quantum information. Optimization of the cavity design by "gentle confinement" yields a high quality factor Q>66000 and small mode volume V approximately 1.1( l/n)(3). In view of experimental applications we consider the influence of material absorption on the cavity Q factors and present a simple interpretation in the framework of a one-dimensional cavity model.