CO2 laser glass processing for high power fiber laser applications

Abstract

High power lasers have been extensively used in industry, military, astrophysics and medicine for decades. Thanks to developments in optical ber technology in terms of transmittance, heat resistance, robustness, stability and power endurance, ber lasers have recently become more favourable compared to conventional laser types such as gas and solid state lasers. Furthermore, high power ber lasers possess advantageous features like compactness, robustness, all- ber and alignment-free operation. Besides advances in high power ber lasers, the structure and power endurance of the critical components as well as their integration quality have been improved. CO2 laser is one the most e ective source in glass processing of optical bers since it provides stable and homogeneous radiation resulting in a clean process. We have tailored optical bers to attain low-loss, high quality, mechanically stable integration points by using CO2 laser radiation. Moreover, we have produced high power ber laser components such as end-cap and ball lens for manipulating the ber laser output beam. By tapering the optical bers, we have fabricated pump and signal combiners which have mode eld adapting properties. The 7x1 pump combiner was integrated to the high power ber laser system developed in our laboratory. Pump source limited power handling capacity of this pump combiner was measured as 850 Wwith an overall e ciency of 98%. In addition, the same pump combiner was adapted to a high power ber laser system which was built by using an in-house fabricated active ber. Finally, we have fabricated a 3x1 laser combiner to combine two in-house ber lasers with an output power of 1 kW and 690 W at 1080 nm wavelength. The maximum combined power was measured as 893 W by using two ports of this combiner with a launched power of approximately 500 W from each of them. The overall e ciency of the combiner was calculated as 93%. On the whole, we have performed successful glass processing by using CO2 laser radiation. As a consequence of optimized, high quality tapering and splicing of optical bers, we have fabricated critical components for high power ber lasers such as end-cap, ball lens, pump and laser combiners.