Methods for 3D photonic structures fabrication

This paper reports first results of a method for the fabrication of 3D photonic structures consisting of "bubbles" within a polymer matrix. A multi-layer resist is exposed with electron-beam lithography, and then developed to form "bubbles" in an underlayer. The layer with "bubbles" is stabilized, another layer is deposited, and a new set of "bubbles" is created after alignment. The advantage of the method is that it allows one to control bubble positions with accuracy of electron-beam lithography, to control the bubble size (0.2-5μm), to fabricate 3D structures (structures of more than 10μm thick with more than 10 layers were fabricated), to create bubbles of various shapes (disks, ellipsoids, squares, triangles, etc.), and to produce photonic crystals with composite cells. Moreover, aperiodical (almost arbitrary) structures can be fabricated, so that arbitrary refractive index distribution could be arranged in 3D space. Optical experiments were made to study light transmission through a 3D photon crystal. A f.c.c crystal consisting of 5-layers was used. Light transmission was measured normal to the crystal and the results obtained agreed with those expected for a photon crystal of this thickness.