Fabrication of PEEK Ag/AgI mid-infrared hollow fiber and transmission reliability study for CO2 laser radiation

Hollow fiber is a crucial means for delivery of mid-infrared laser radiation and has a wide range of applications in laser surgery and other fields. At present, there is still a lack of low-cost, highly flexible plastic hollow fiber that can reliably transmit mid-infrared laser with low loss. In this study, flexible Poly ether ether ketone (PEEK) tubing material was selected as the structural tube for establishing a robust plastic Ag/AgI mid-infrared hollow fiber. Fiber samples with inner diameters of 1.0, 1.5 and 2.0 mm were prepared using plasma treatment and dynamic chemical liquid deposition processes. The transmission losses for CO2 laser of the 1.0-, 1.5-and 2.0-mm-bore PEEK Ag/AgI hollow fibers increased from 0.40, 0.18 and 0.10 dB/m to 2.35, 1.60 and 1.05 dB/m, respectively, as they were bent at an angle from 0 degrees to 180 degrees with a radius of 15 cm. The hollow fibers could stably transmit CO2 laser in high (120 degrees C) and low (-78.5 degrees C) temperature environments. After undergoing 100 h of accelerated humidity-heat aging (85 degrees C, 85 % RH) and 10 cycles of high-low (-40 -85 degrees C) temperature cycling treatment, the transmission loss remained almost unchanged. The PEEK Ag/AgI hollow fiber exhibited high energy damage threshold and it could stably deliver a 10 -20 W CO2 laser beam for 20 min to 5 h when bent at a 25 cm radius and a 90 degrees angle. The current research provides a possible approach for developing low-cost, highly flexible, low-loss and highly reliable mid-infrared hollow fibers. It is helpful to promote the applications of CO2 laser in laser medicine, intelligent manufacturing and sensing.