Improving the Efficiency of Quasi-Optical Bragg Reflectors

Abstract

In the analysis of propagation of wave beams in quasi-optical transmission lines, the loss rate and transformation of modes by various elements of the transmission line are of great importance. The effects occurring when a spatially bounded, obliquely incident wave beam is reflected from a Bragg resonator being a periodic, plane-layered medium with varied dielectric permittivity are considered. Such a reflector can be used as a frequency-selective element of the transmission line. Since the reflection coefficient of a plane wave from the Bragg reflector depends on its incidence angle, there occurs a transformation of the reflected beam. Analytical expressions for the beam displacement, the angle of deflection of the beam from the mirror reflection direction, and the wavefront curvature variation have been obtained. The influence of the mentioned effects on characteristics of the reflected wave beam in the main band of the Bragg reflector is numerically analyzed. The possibility of compensation for these distortions is considered.