Researchers from the Karlsruhe Institute of Technology (KIT) in Germany have made a breakthrough in the field of photonic integrated circuits (PICs) with the development of 3D printed microlenses. These microlenses, called facet-attached microlenses (FaML), offer a solution to the scalability challenges faced by PIC-based systems.
PICs have the potential to revolutionize various applications, but the packaging and assembly of these circuits have proven to be significant obstacles. The conventional approach of butt coupling, where device facets are placed in close proximity or in direct contact, requires precise alignment and matching of mode fields, making the assembly process complex and costly.
Using multi-photon lithography, the KIT research team was able to 3D-print FaML with high precision onto the facets of optical components. This technology allows the shaping of emitted beams through designed refractive or reflective surfaces, eliminating the need for active alignment. The FaML concept also enables the insertion of discrete optical elements into the beam paths between PIC facets.
The researchers conducted several experiments to validate the effectiveness of their approach. They achieved low insertion losses and alignment tolerances in coupling fiber arrays to silicon photonic chips.
They also demonstrated contactless pluggable fiber-chip interfaces and free-space transmission using machine-vision techniques. Additionally, they successfully coupled planar devices through non-planar beam paths with ultra-low back-reflection.
The use of 3D-printed microlenses represents a significant advancement in the development of PICs. It eliminates the need for costly active alignment, simplifies assembly processes, and enhances scalability.
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