Reduction of propagation loss to 0.1 dB/mm: flat-core channel waveguides consisting of periodic structures

We successfully fabricated channel waveguides utilizing photonic crystal (PhC) dispersion having a very low loss of ∼0.1 dB/mm by the autocloning method. We achieved the loss reduction by improving the fabrication condition and adjusting the core width. The result of propagation loss can be regarded as a "milestone," and it enables us to realize practical PhC circuits that contain functional components such as chromatic dispersion equalizers and high Q wavelength filters.