Versatile Micro Optical Coupling Platform Created by Selective Laser Etching and Smoothing of Thin Glass

In this contribution we are presenting a highly adaptable approach to integrate and couple discrete light sources, optical fibers and optical-electrical components in thin film metallized and laser structured glass packages and platforms. Almost arbitrary mechanical features like pedestals, cavities, v-grooves, mounting holes and glass vias can be structured with µm accuracy, to serve as 3D mounting and holding features for discrete optical and opto-electronic components. This high accuracy enables passive alignment when inserting or stacking components and thin glass parts. Generic examples of different vertically and horizontally coupling set-ups are shown, realized in either 3D structured single or stacked glass assemblies. Glass parts can also be thin film metallized and structured for electrical routing and thermal contacting of laser and driver chips, either on or inside glass – as through-glass-via TGVs. The key process selective laser etching SLE can also integrate optical features along mechanical ones. This opens a huge design space for optical coupling directly realized in coupling stacks or platforms: Lenses and mirrors with complex aspherical or free form shapes can be structured. Their remaining nanoscopic roughness of typically 1-2 µm after SLE processing can be smoothed in a further step of applying pulsed CO2 laser beams. This way optical surface qualities with 20 nm or better can be reached. We observe that in the smoothing process etched surfaces with aspherical shape as designed are conserved. Currently lenses with diameters as small as 250 µm have been fabricated and optically characterized. This scalable approach currently is extended to fabricating customizable 1D and 2D arrays of lenses and mirrors, while also pushing pitch and diameters down to 40 µm.