Higher-Order Scattering Losses in Dielectric Waveguides

Higher-Order Scattering Losses in Dielectric Waveguides By D. MARCUSE (Manuscript received April 17, 1972) This paper discusses the scattering losses of dielectric slab waveguides that are caused by higher-order grating lobes of the sinusoiclally distorted core-cladding interface. The results of this paper are used in a companion paper to evaluate the radiation losses of midtimode guides with intentional mode coupling. An exact system of equations is derived for the amplitudes of all grating orders. This system is used to derive first- and second-order approximations that hold for small amplitudes of the sinusoidal interface distortion. The theory is used to derive formulas for the average power loss coefficient for first- and second-order scattering processes.