imec Ball-Lens Scheme Cuts Photonic Chip-to-Board Coupling Loss to 3.4dB via Substrate Vias
jwt0625 · x · 2026-11-05
The author shares two papers on chip-to-board optical coupling for silicon photonics: a ball lens embedded in a package-substrate through-via enables direct photonic chip-to-board coupling.
Key details
- Path: output grating with metal reflector couples light downward through a ruby-doped sapphire ball lens in the substrate via, then a 40° Au-coated mirror plug feeds board-level polymer waveguides connected to multimode fiber.
- imec's measured loss for grating + ball + mirror is just 3.4dB at 1310nm.
- Full fiber-to-fiber link loss is 12dB (input grating 5dB, 4mm SOI waveguide 1.2dB, 3cm polymer waveguide 2.4dB).
- Photos show the alignment test setup with the ball-lens-embedded substrate and connectorized polymer waveguides.
Such alignment-tolerant, package-integrated coupling is a key building block for co-packaged optics and board-level optical interconnects.
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