Small-bore hollow waveguides for delivery of 3-µm laser radiation

Flexible hollow glass waveguides with bore diameters as small as 250 µm have been developed for 3-µm laser delivery. All the guides exhibit straight losses between 0.10 and 1.73 dB/m, and the loss increases to between 2.4 and 5.1 dB/m upon bending 1 m of the guides into 15-cm-diameter coils. This behavior is shown to depend strongly on the launch conditions and mode quality of the input beam. The waveguides are capable of efficiently delivering up to 8 W of Er:YAG laser power with proper input coupling, and they are suitable for use in both medical and industrial applications.