A novel coupling configuration consisting of a tapered slab waveguide with a wedge-shaped nonlinear cladding is proposed. Coupling characteristics for TE waves are analyzed by means of the beam propagation method. The proposed configuration is less sensitive to the offset between coupled waveguides than is the configuration with a homogeneous non-linear cladding.

Power dependent coupling efficiency for a butt-joined configuration using nonlinear cladding is analyzed by the beam propagation method. This configuration is not so sensitive to the angular misalignment as well as the offset between coupled waveguides on condition that the input power is appropriate to assure the propagation of spatial soliton.