Polarization-maintaining hollow glass waveguides with noncircular bore

Hollow waveguides are made from square and rectangular glass tubing for the transmission of polarized CO2 laser radiation. These hollow noncircular cross section glass waveguides have Ag and AgI thin film coatings deposited on the inside surface using liquid-phase chemis- try techniques. The losses for straight square (5003500 mm) and rect- angular (22531250 mm) hollow glass waveguides at 10.6 mm were 0.8 and 2.2 dB/m, respectively. The degree of polarization is more than 90% for the rectangular waveguides, and this degree of polarization is pre- served when rectangular guides are bent or twisted to rotate the polar- ization.