Low-loss optical transmission through bent hollow metal waveguides

The transmission of 10.6-μm light in bent metal-walled waveguides of rectangular cross section is described both theoretically and experimentally. It is shown that the bending loss per angle of bend in these waveguides is explicitly independent of waveguide height, bend radius, and light wavelength, depending only on the reflectivity of the waveguide walls. In confirming experiments, guides with aluminum walls showed 95% transmission per radian of bend for radii in the range from less than 1 cm to 1 m.