High-density integrated optics

This paper presents two-dimensional (2-D) finite difference time domain (FD TD) simulations of low-loss right-angle waveguide bends, T-junctions and cr ossings, based on high index-contrast waveguides. Such structures are essen tial for the dense integration of optical components. Excellent performance characteristics are obtained by designing the waveguide intersection regio ns as low-Q resonant cavities with certain symmetries and small radiation l oss. A simple analysis, based on coupled mode theory in time, is used to ex plain the operation principles and agrees qualitatively with the numerical results.