Abstract

A novel hollow, multilayered O-type dielectric lightguide is proposed for use at millimeter wave, submillimeter wave, and near-infrared frequencies. In this frequency range closed-pipe metallic waveguides and optical fibers exhibit prohibitive material losses. In contrast to conventional light-guides, energy is not guided by surface waves in this structure; instead, guidance is accomplished in the air-core region by reflection of incident radiation from the inner air-dielectric interface. This results in a minimization of the energy confined to the lossy dielectric material. The number of layers used, layer thicknesses, and layer composition are chosen to maximize reflection at the inner interface for a prescribed range of incidence angles, in close analogy to the process used in design of dichroic laser cavity mirrors. Fabrication techniques perfected in construction of optical fibers can be readily adapted to this new configuration. Numerical results demonstrating feasibility with realistic material parameters are presented. Applications of such a guide in construction of optical devices such as transversal filters are discussed.

© 1986 Optical Society of America