Enhanced energy density and optical absorption in a 3D photonic band gap cavity with finite support

The confinement of light to a tiny volume is an important drive in nanophotonics. Notable applications such as trapping of photons, sensing for biotechnology, control of spontaneous emission and Cherenkov radiation, lasing, and cavity QED [1-3]. While much work has been done on microspheres, micropillars, microdisks, plasmonic cavities, toroidal rings, or 2D photonic crystals, there are a few studies on cavities in a three-dimensional (3D) photonic band gap crystal. Therefore, we study the transport and storage of light in a cavity in a 3D photonic band gap crystal slab. The crystal has finite support as it is surrounded by free space, as in experiments. We employ the finite element method (on a computer cluster) to model the diamond-like inverse woodpile crystal that consists of two orthogonal arrays of pores in a high-index dielectric such as silicon and that has experimentally been realized by CMOS-compatible methods [4]. The resonant cavity is formed in the proximal region of two selected orthogonal pores with a radius smaller than the ones in the bulk of the crystal [5].