Comparison of Three-Dimensional Photonic Crystal Slab Waveguides with Two-Dimension Photonic Crystal Waveguides: Efficient Butt Coupling into these Photonic Crystal Wavebudies

Butt-coupling into photonic crystal waveguides is computationally examined for a two-dimensional photonic crystal and a photonic crystal slab. The particular photonic crystal slab we study consists of a silicon-on-insulator (SOI) substrate with a triangular array of holes, in which the silicon layer is the optical guiding layer. The coupling efficiencies of the two-dimensional system and the slab system differ. The slab system only supports a small range of frequencies in which a guided mode exist. In this frequency range, the coupling efficiency is comparable to that of the two-dimensional system, and its value is around 0.8. For the higher frequencies, where resonances only exist for the slab system, the coupling efficiency is much lower. Finally, the losses of these resonances are discussed.