Guided modes in photonic crystal slabs

We analyze the properties of two-dimensionally periodic dielectric structur es that have a band gap for propagation in a plane and that use index guidi ng to confine light in the third dimension. Such structures are more amenab le to fabrication than photonic crystals with full three-dimensional band g aps, but retain or approximate many of the latter's desirable properties. W e show how traditional band-structure analysis can be adapted to slab syste ms in the context of several representative structures, and describe the un ique features that arise in this framework compared to ordinary photonic cr ystals. [S0163-1829(99)00832-2].