An efficient approach to minimize radiation loss at index discontinuities of optical waveguides

A transverse mode matching (TMM) approach is proposed for the reduction of radiation loss in dielectric waveguides with an array of index discontinuities. In this approach an index-modulated buffer layer is inserted between the core and substrate of the waveguide to match the transverse modal profiles of the guided modes at the discontinuities. Application of this approach to the design of periodic waveguides shows one order-of-magnitude reduction in the radiation loss of TE modes due to the insertion of the buffer layer.