Effect of a strip index of refraction profile on the radiation from curved rectangular dielectric waveguides

The need in the development of optical integrated circuits for the introduction of sharper bends in the waveguides, particularly with the objective of reducing size, is addressed. Since a reduction of the curvature radius causes increased radiation with a potential increase of interaction between integrated components, it is important to search for ways of reducing this radiation. The influence of the index-of-refraction profile on the radiation from curved optical waveguides is considered as a means to achieving this. The effect of the introduction of a step index profile in the rectangular dielectric waveguide is investigated, thereby extending the analysis of E.A. Marcatili (1969) to this new class of waveguide. Expressions were obtained for the phase constants along the x and y directions of a curved rectangular dielectric waveguide with a step index of refraction profile, including the conversion coefficient between the straight and curved portions of the waveguide and the attenuation coefficient.<>