Design and fabrication of impurity band-based photonic crystal waveguides for optical delay lines

Abstract

We have designed, fabricated, and characterized efficient optical delay lines for ultrashort pulses based on photonic crystal waveguides formed by coupled defects. The basic structure consists of one-dimensional cylindrical air holes formed in silicon on silicon dioxide ridge waveguides. The defects are created by intentionally increasing the separation of two neighboring air holes. Through proper design, quasiflat impurity bands located at ∼1.55 μm can be successfully obtained. In addition, the wavelength tunability of the impurity bands was clearly demonstrated. Good agreement was found between the experimental observations and numerical simulations.