Transmission properties of infrared hollow fibers produced by drawing a glass-tube preform

To produce long and flexible hollow optical fibers for mid-infrared lasers at a low cost, hollow fibers are fabricated by using a glass drawing technique. When the wall thickness of the glass tube is properly designed and controlled, the fiber shows a low loss at a desired wavelength. By applying pressure into the tube preform, the glass capillary with a thin glass wall is drawn, and this effectively reduces the absorption loss in the glass material. The measured loss of 40-cm long fiber with an inner diameter of 320 μm is 1.7 dB for an erbium: yttrium aluminum garnet laser light with a wavelength of 2.94 μm.