Laser-based, on-chip fabrication of glass-based core-cladding waveguides

Abstract

Photonic integrated circuits (PIC) have been established for miniaturized, on-chip optical systems. Current approaches for producing PICs mostly rely on semiconductor processing technologies, which are complex and costintensive. A promising alternative with the potential to revolutionize PIC fabrication is additive manufacturing (AM), which offers the opportunity to develop tailored and customized waveguide designs for functionalities needed in fast-evolving modern applications like the Internet of Things. Here, an AM technology called laser glass deposition (LGD) is presented for the production of on-chip core-cladding waveguides based on fused silica. Commercially available glass fibers with a diameter of 125 µm are fused onto a quartz glass substrate using a CO 2 -laser in a 2.5D-printing process. Test series are performed to determine the process window to reach a stable connection between fiber and substrate while maintaining the fiber´s optical functionality. To enable efficient light coupling into the waveguide, the fiber end facets are laser cleaved after the deposition within the same process environment. Again, parameter studies are performed to reach a high surface quality. Both the waveguides and the cleaved surfaces are characterized using different imaging techniques. In addition, the optical properties of the generated waveguides are analyzed.