A three-dimensional optical photonic crystal with designed point defects

Photonic crystals(1-3) offer unprecedented opportunities for miniaturization and integration of optical devices. They also exhibit a variety of new physical phenomena, including suppression or enhancement of spontaneous emission, low-threshold lasing, and quantum information processing(4). Various techniques for the fabrication of three-dimensional (3D) photonic crystals-such as silicon micromachining(5), wafer fusion bonding(6), holographic lithography(7), self-assembly(8,9), angled-etching(10), micromanipulation(11), glancing-angle deposition(12) and autocloning(13,14)-have been proposed and demonstrated with different levels of success. However, a critical step towards the fabrication of functional 3D devices, that is, the incorporation of microcavities or waveguides in a controllable way, has not been achieved at optical wavelengths. Here we present the fabrication of 3D photonic crystals that are particularly suited for optical device integration using a lithographic layer-by-layer approach(15). Point-defect microcavities are introduced during the fabrication process and optical measurements show they have resonant signatures around telecommunications wavelengths (1.3-1.5 mum). Measurements of reflectance and transmittance at near-infrared are in good agreement with numerical simulations.