Imec Demonstrated 400 Gbps Silicon Optical Link
The research-stage demonstration achieved 100 GHz bandwidth, potentially reducing optical power consumption in data centers.
Updated on Sept. 22, 2026 in Semiconductors
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Imec has successfully demonstrated a 400 Gbps optical link utilizing a Germanium/Silicon (Ge/Si) avalanche photodiode. This research-stage development achieves a 100 GHz bandwidth and a 3 dB improvement in receiver sensitivity.
Why it matters
The 3 dB sensitivity gain provides additional link margin, which allows engineers to either reduce overall laser power consumption or compensate for higher optical signal losses in high-speed networks. This capability is critical for scaling data transmission speeds to meet the demands of modern computing infrastructure.
The Ge/Si avalanche photodiode operates at 5 V and achieves 1.8 A/W responsivity across O- and C-bands. The device utilizes a SACM (Separate Absorption, Charge and Multiplication) architecture modified by removing the charge layer and scaling the multiplication layer width to below 100 nm.
The players
Imec
A nanoelectronics and digital technology research hub specializing in silicon process integration and semiconductor architecture development.
The details
The device functions as an avalanche photodiode, a specialized sensor that converts light into electrical current by using an internal multiplication process to amplify signals. By reducing the multiplication layer width to under 100 nm and eliminating the charge layer, the design optimizes carrier transit times to reach 100 GHz. Imec paired this photodiode with an Electro-Absorption Modulator (EAM)—a device that controls light intensity using an electric field—capable of speeds exceeding 110 GHz.
Timeline
In 2025, Imec unveiled a C-band Ge/Si EAM with a bandwidth exceeding 110 GHz.
In September 2026, Imec demonstrated the complete 400 Gbps optical link.
The Tech Race
This demonstration sits at the cutting edge of silicon photonics research as labs race to push integrated optical links past current throughput bottlenecks. It marks a significant milestone in Imec's roadmap to replace legacy discrete components with highly integrated, high-bandwidth optical engines.
This research remains in the lab and is not yet available in commercial networking hardware. If successfully integrated, the design will eventually enable data center operators to deploy faster, lower-power optical links for next-generation network traffic.
The takeaway
The move to a sub-100 nm multiplication layer demonstrates that silicon-based architectures can continue to scale alongside demands for 400 Gbps and faster throughput. Watch for the next phase of research involving the integration of these photodiodes with CMOS receiver electronics.
What happens next
Future developments include testing the reliability of the avalanche photodiode across broader temperature and power ranges, as well as integrating the device with high-speed receiver electronics.
Further reading
For more on the current state of optical interconnects, see our Semiconductors section.
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