Weak Guidance in Bent and Unbent Four-Layer Planar Waveguides-A Comparative Study of Dispersion Curves

A comparative study has been made of the dispersion curves of a four-layer bent and an unbent dielectric slab waveguide under the assumption of the weak guidance approximation. It has been noticed that the introduction of a slight bend to a planar waveguide results in mode-proliferation, and lower order modes show no cutoff at all. This anomalous behaviour of the dispersion curves is not seen in the case of an unbent waveguide structure.