Design of microcavities in diamond-based photonic crystals by Fourier- and real-space analysis of cavity fields

We present the design of two-dimensional photonic crystal microcavities in thin diamond membranes well suited for coupling of color centers in diamond. By comparing simulated and ideal field distributions in Fourier and real space and by according modification of air hole positions and sizes, we optimize the cavity structure yielding high quality factors up to Q=320,000 with a modal volume of Veff=0.35(λ/n)3. Using the very same approach we also improve previous designs of a small modal volume microcavity in silicon, gaining a factor of 3 in cavity Q. In view of practical realization of photonic crystals in synthetic diamond films, it is necessary to investigate the influence of material absorption on the quality factor. We show that this influence can be predicted by a simple model, replacing time consuming simulations.