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The large bandwidth demand in long-distance telecom networks lead to single-mode fiber interconnects as result of low
dispersion, low loss and dense wavelength multiplexing possibilities. In contrast, multi-mode interconnects are suitable
for much shorter lengths up to 300 meters and are promising for optical links between racks and on board level. Active
optical cables based on multi-mode fiber links are at the market and research in multi-mode waveguide integration on
board level is still going on. Compared to multi-mode, a single-mode waveguide has much more integration potential
because of core diameters of around 20% of a multi-mode waveguide by a much larger bandwidth. But light coupling in
single-mode waveguides is much more challenging because of lower coupling tolerances. Together with the silicon
photonics technology, a single-mode waveguide technology on board-level will be the straight forward development goal
for chip-to-chip optical interconnects integration. Such a hybrid packaging platform providing 3D optical single-mode
links bridges the gap between novel photonic integrated circuits and the glass fiber based long-distance telecom
networks.
Following we introduce our 3D photonic packaging approach based on thin glass substrates with planar integrated
optical single-mode waveguides for fiber-to-chip and chip-to-chip interconnects. This novel packaging approach merges
micro-system packaging and glass integrated optics. It consists of a thin glass substrate with planar integrated singlemode
waveguide circuits, optical mirrors and lenses providing an integration platform for photonic IC assembly and
optical fiber interconnect. Thin glass is commercially available in panel and wafer formats and characterizes excellent
optical and high-frequency properties. That makes it perfect for microsystem packaging. The paper presents recent
results in single-mode waveguide technology on wafer level and waveguide characterization. Furthermore the integration
in a hybrid packaging process and design issues are discussed.
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