Guided modes with flat photonic bands in textured metallic microcavities

Summary form only given. The use of planar microcavity structures to control spontaneous emission from optical devices is now a well-established technique. The simplest geometry is that of a pair of planar mirrors separated by a distance of order the wavelength of light, with the emissive species situated between the two mirrors. It has been clearly demonstrated that the boundary conditions imposed by such planar microcavity systems can modify the spatial and spectral distribution of the emitted radiation from such devices, and also the spontaneous emission lifetime of the emitter. However, the extent to which spontaneous emission may be controlled is limited by the planar symmetry of the microcavity. In order to modify the spontaneous emission process further, the dimensionality of the system needs to be reduced, and it is this that we have sought to do in the present study. We first examine the case of a solid-state microcavity textured with a single, periodic corrugation. We explore how the depth of the corrugation and the waveguide thickness affect the width of the band gap produced in the dispersion of the guided modes. We discover that substantially flat bands are generated for the dispersion of the waveguide modes supported by the structures. We then experimentally examine band gaps produced in the guided modes of a two-dimensionally textured microcavity, and demonstrate the existence of a complete band gap for all directions of propagation of the lowest-order TE-polarized mode.