Enhancement of spatial modal overlap for photonic crystal nanocavities

New photonic crystal nanocavity geometries are suggested and numerically studied. Such nanocavities have an enhanced spatial modal overlap. It is also possible to independently tune the cavity resonance modes frequencies. The case of degenerate resonance modes is studied. Nanocavities with circular holes and slots are studied. It is demonstrated that the nanocavities with slots allow one to enhance the spatial overlap of orthogonally polarized resonance modes. It is shown that closed slots can be used to increase the quality factor of the nanocavities.