A new method is proposed for making sharp bends with low radiation losses in dielectric optical waveguides. By modifying the transverse refractive-index profile at curved sections both the pure bend and the transition losses can be minimized. The optimum gradient-index profile requires an inhomogeneous medium. But in practice this can be replaced by a layered medium. By using four homogeneous layers the permitted radius of curvature of a slab waveguide can be reduced, e.g., from 6400 to only 100 wavelengths.
© 1983 Optical Society of America
Ernst-Georg Neumann and Wolfgang Richter, "Sharp bends with low losses in dielectric optical waveguides," Appl. Opt. 22, 1016-1022 (1983)