Hollow glass waveguides with a 250-mu m i.d. have been fabricated with
a liquid-phase deposition technique that uses silica tubing as a base
material. The losses of the 250-mu m-bore guide measured at CO2 laser
wavelengths are as low as 2.0 dB/m. The straight losses for the hollo
w guides are in good agreement with theoretically predicted losses as
a result of the nearly ideal structure of the guides. It is also shown
that the guides have low bending losses, a nearly pure-mode delivery,
and good high-power laser transmission. By proper design of the diele
ctric thickness, the guide is also able to deliver Er:YAG laser energy
with a low loss of 1.2 dB/m for the 320-mu m-bore waveguide. Because
the hollow glass waveguide is very flexible and robust, it is quite su
itable for medical applications.