Hole depth- and shape-induced radiation losses in two-dimensional photonic crystals

A phenomenological model is adopted to study three-dimensional radiation losses in two-dimensional (2D) photonic crystals (PhC) deeply etched in a step-index waveguide. In the case of low vertical refractive index contrast, losses are modeled in a 2D approach and out-of-plane scattering is translated into an effective imaginary index in the air holes. The case of truncated-cone holes is analytically solved. Depth and shape contributions to losses are extracted showing that the verticality of the hole sidewalls is a fundamental parameter. In order to validate the model, the case of a 2D triangular lattice etched through an InP/GaInAsP slab waveguide is studied both theoretically and experimentally. (C) 2003 American Institute of Physics.