Assembly of a photonic wavelength-division multiplexing device using laser-based soldering

Miniaturization of photonic devices is required by various applications such as data storage and processing, optical communications, and metrology. This request can be met by new optical designs, miniaturized components, and advanced packaging technologies. Design, assembly, and characterization of a miniaturized photonic wavelength-division multiplexing (WDM) device for optical measurements are presented. The device features the use of gradient index lenses (GRIN-lens) and the utilization of an adhesive free, laser-based joining technology. Solderjet Bumping offers flux-free soldering in a localized inert nitrogen atmosphere with minimized input of thermal energy, thus allowing for the joining of fragile materials such as glass or brittle ceramics. The proposed system design consists of a system platform made of borofloat BF33 with a footprint of approx. 30x20 mm2. Mechanical stops also made of borofloat glass, fiber-ferrules with a length of approx. 5 mm, and GRIN-lenses with a length of 4.05 mm are attached to the base-plate by solder joints. The solder process uses tin-silver-copper (Sn3Ag0.5Cu) solder spheres with a diameter of 200, 400, and 760 ?m. A fiber-to-fiber coupling efficiency of 72 % is demonstrated using uncoated components.