Losses at corner bends in dielectric waveguides.

An approximate technique based on a sum rule is used to treat mode conversion at corner bends in dielectric waveguides. Matrix elements which describe the mode coupling are expressed as spatial integrals over electromagnetic field distributions for the guided modes. These matrix elements provide information on the magnitude, average propagation constant, and coherence of power propagating in radiation modes. Numerical results are obtained for single mode and multimode slab waveguides, and implications for the design of low-loss interconnections and mode converters for integrated optics are discussed.