Waveguide and guided-wave devices consisting of heterostructured photonic crystals

We report a strategy for the industrialization of photonic-crystal-based optical devices, starting with a review of the requirements for passive photonic crystal components. Although they have remarkable properties, such components are difficult to couple to/from optical fibers and have a relatively large propagation loss. We present an approach for meeting the requirements by using heterostructured photonic crystals fabricated by the autocloning technology. A low-loss, simple structured waveguide and sophisticated functional blocks (such as a resonator) can be integrated by a simple process. We first prepare a substrate patterned and corrugated by electron beam lithography and dry etching. Ta₂O₅/SiO₂ multilayers are repeatedly deposited on the substrate, and no other process is needed to complete the chip. After dicing and polishing, the waveguide can be butt-jointed with an optical fiber, and the loss is estimated as 0.1 dB/mm. A resonator with Q = 11,700 is also demonstrated. Recent progress and the future outlooks for the technology are also discussed.