The scattering properties of dielectric gratings having asymmetric triangular profiles are determined by a simple approach that views the grating structure as a double set of parallel planes. The energy of an incident surface wave is then scattered in preferential directions that are consistent with the grating periodicity and with a Bragg condition. As a result, the triangular shape can be chosen so that scattering occurs mostly into the region above the grating or into that below it, thus making it possible to maximize the efficiency of beam couplers or other devices. This desirable blazing property can be achieved by satisfying simple design criteria that are obtained from the scattering approach presented here. The range of grating parameters for strong blazing is derived, and gratings with trapezoidal profiles are also discussed.
© 1980 Optical Society of America
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