ABSTRACT

While methods to fabricate PhCs have continued to develop, those for use at near-visible frequencies require feature sizes of the order of a fraction of a micrometer and at that scale there can still be signicant challenges in producing satisfactory structures. Onedimensional (1D) PhCs (dened as PhCs, such as multilayer structures, that are periodic in one dimension and have essentially uniform properties in the other two dimensions) for optical applications can be produced with very high delity, and atomic monolayer accuracy in the case of molecular beam epitaxy. However, two-dimensional (2D) and threedimensional (3D) PhCs are more demanding to fabricate and the imperfections are more signicant with the present level of technology. For example, synthetic opals are made from silica spheres, which are grown from a supersaturated solution and ƒuctuate in size and shape.2 Also synthetic opals and other self-assembled structures can contain localized defects such as vacancies and stacking faults.3 2D PhCs for the optical band can be fabricated by lithography and subsequent etching or by focused ion beam etching but their detailed features can deviate from the desired shape, size, or position and such structures can also suffer from the effects of surface roughness.