Ray model for transmission of metallic-dielectric hollow bent cylindrical waveguides.

The problem of transmitting CO(2) laser radiation through metallic or metallic with inner dielectric coating (metallic-dielectric) bent hollow cylindrical waveguides is investigated using a ray model. Computer calculations of transmission as a function of the geometrical dimensions of the waveguide are performed. The coupling of laser radiation at the entrance of the waveguide is also taken into account. The theoretical calculated transmission is compared with previously published experimental data and good agreement is obtained for a large range of curvatures. The devised ray model contributes to a better understanding of the role of the dielectric layer in the metallic-dielectric waveguide, increasing the transmission of the radiation. The calculation of the transmission as a function of the radius of the cross section of the waveguide shows that, for a best metallic-dielectric waveguide, an optimal cross-sectional diameter appears where the transmitted energy is maximum. The method presented will be of value as a tool in the design of hollow cylindrical waveguides.