CEA-Leti Develops Active Optical Interposers to Connect Chiplets

By Pat Brans, EETimes Europe (October 1, 2024)

Researchers at Leti and companion institute CEA-List are developing active optical interposers that would connect a large number of chiplets with minimal latency.

In 2019, CEA-Leti became the first organization to demonstrate successful integration of chips onto an active interposer using 3D architecture. Researchers at Leti and companion institute CEA-List are now building on that work to develop active optical interposers that would connect a large number of chiplets with minimal latency. The effort targets complex systems-in-package as the industry produces chiplets in ever-increasing numbers on ever-larger wafers.

At the Leti Innovation Days 2024 event in Grenoble, France, this summer, EE Times Europe sat down with two CEA researchers to talk about the recently developed Starac, a chiplet-based optical network-on-chip (ONoC) demonstrator built on an active optical interposer that draws on Leti’s earlier achievements in electronic interposers. “We kept the capability to route information between chiplets without needing to hop between a lot of intermediate chiplets,” said Yvain Thonnart, senior researcher at CEA-List. “And by using photonics, we plan to reduce latency by a large factor over our previous work and compared with what’s done in industry today.”

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