Practical and theoretical modal analysis of photonic crystal waveguides

We present practical and theoretical, stage-by-stage analysis of light propagation around a 90° corner in a two-dimensional photonic crystal waveguide. Using a series of different samples we quantify the coupling efficiency between the conventional ridge waveguide and the photonic crystal waveguide as well as the bending efficiency around the 90° corner. From this, the transmission spectra indicate nearly 90% bending efficiency. We compare the experimental results to the three-dimensional simulated band diagram and field distribution. The propagating defect modes are identified in detail and we show that efficient transmission around sharp bends in photonic crystal waveguides can be achieved for leaky modes above the light line with short photonic crystal sections.