Transmission characteristics of a curved hollow silica waveguide at 10.6 µm

Experimental measurements of the transmission and mode output of a 2 mm bore hollow silica waveguide have been made as a function of its radius of curvature. Even a small amount of bending is observed to have a significantly detrimental effect on both transmission and mode output. The results are presented and compared to theoretical predictions. One interesting conclusion of the work is that as the waveguide is bent, coupling of optical energy occurs from the fundamental waveguide mode into higher order modes which have lower attenuation in the curved waveguide. The result is that higher transmission is measured than would have been predicted based on the sole existence of the fundamental mode.