Generation of functional curved waveguides by CO2-laser based deposition of coreless fused silica fibers

There is an increasing demand for highly integrated optical and optoelectronical devices that provide active laser emission, adaptability and low optical losses. A well-established production technology for customized structures with high functionality and geometrical exibility is additive manufacturing (AM). It enables new constructional degrees of freedom to overcome the limitations of substractive material processing such as milling and drilling. Commercial AM systems for metals and polymers are ubiquitous; whereas glass AM systems almost exclusively exist in scientific environments. Laser glass deposition welding allows the AM of waveguides by fusing coreless fused silica fibers with a diameter of 400 µm and a 50 µm thick polymer coating onto a fused silica substrate. The deposition process is performed with defocused CO2-laser radiation (10.6 µm). Based on laser deposition welding, the fiber is fed laterally into the processing zone and is melted or fused by the incoming laser beam. In order to achieve a sufficient coupling of laser radiation into and out of thefibers, a proper cleaving process for the end faces has been established. The cleaving is performed with a CO2-laser based process for optimized and reproducible results. In this contribution, the focus is on the manufacturing of bended waveguides and the feasible bending radii, which can be accomplished during the deposition process. The influence of the bending radius on the guiding efficiency is investigated. Therefore, the light transmission and beam profile of the deposited fibers is measured and compared with an untreated one. Furthermore, the appearance of the cleaved end faces and the internal stress in the glass substrate are characterized. Functional, nearly stress-free curved and straight waveguides for light transmission with high position stability are achieved, which opens a wide range of applications for optical system integration.