Photonic wire bonds and facet-attached micro-lenses are 3D freeform structures that enable high design flexibility while maintaining low loss, reproducibility, high reliability and packaging compatibility. These attributes are crucial for high-volume production of compact optical integration platforms in advanced photonics packaging.
The rapid advancements in optoelectronic devices have driven a growing demand for developing photonic integrated circuits (PIC) that leverage cutting-edge active and passive
components, which are often fabricated on different material platforms. For instance, a PIC module could involve hybrid integration of an indium phosphide (InP) based device such as a laser and a lithium niobate-based device such as a ring modulator. However, for packaging and assembling such a hybrid multi-chip module there remains significant technical and commercial challenges that consequently hinders the full commercialization of photonic systems.
The fundamental issue behind photonic integration is to achieve low optical loss when coupling photonic chips and components. This requires both careful matching of mode fields and precise alignment of photonic chips down to hundreds of nanometers precision to ensure efficient light transmission. One solution for assembly of such photonic systems is to use so-called active alignment techniques where the optical coupling efficiency is continuously monitored and optimized during the alignment process. However, this becomes particularly complex for photonic chips with a mode field size below 2 µm, such as semiconductor-based photonic chips with high-index contrast waveguides. Additionally, when chips with different mode field sizes are involved, further complexity arises as elements such as micro-lenses are needed.
Furthermore, in industrial mass production, processes such as mode matching and alignment must be fast and reproducible as speed and yield are critical to cost-effectiveness. Moreover, the reliability of packaged assemblies under various environmental conditions must be ensured, with requirements differing across applications such as tele- and data- communication, 3D sensing, e.g. Lidar as well as quantum applications. Hence, despite photonic devices used for such specific applications are made with sophisticated processes from sometimes exotic material platforms, the optical packaging or integration process remains in most cases the biggest cost driver.
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