Low-loss singlemode waveguide and fibre bends

A new theoretical strategy for reducing bend loss is presented. It is based on the concept of introducing both depressed and increased index regions into the cladding of planar waveguides on the outside of the bent core. A similar strategy can be applied to optical fibres, in both cases, the bending loss is reduced beyond that achievable with the presence of depressed regions alone in the cladding.