Fabrication of Two-Dimensional Photonic Crystal Slab Point-Defect Cavity Employing Local Three-Dimensional Structures

The two-dimensional photonic crystal cavities employing local three-dimensional structures are investigated. Donor-type cavities with small and shallow holes are examined as examples of cavities with a local three-dimensional structure. It is shown that both the far-field and near-field patterns of the cavities can be controlled by the addition of small and shallow holes. The fabrication of such structures using a focused ion beam is proposed and investigated. Residual gallium ions, used in fabrication with a focused ion beam, lead to optical absorption; these gallium ions can be removed by heat treatment at 800 °C. The near-field pattern of a fabricated three-dimensional cavity is measured, and is shown to be consistent with a theoretical analysis.