IMEC Introduces World's First 110GHz+ C-Band GeSi EA Modulator

The nanoelectronics research center IMEC from Belgium announced the successful completion of a significant trial: the fabrication of a 110GHz C-band GeSi electro-absorption modulator on a 300mm silicon photonics platform.

Achieving a net data rate of 400Gb/s per lane and optimized for compactness, low latency, and high energy efficiency, imec says its modulator “establishes the foundation for next-generation optical IM/DD (intensity modulation with direct detection) links that interconnect data center racks and blade servers in a simple and cost-effective way.”

imec says the technology will be key to meeting the demands of AI applications that rely on faster, more efficient machine learning training. Meeting this challenge calls for short-reach, scale-up interconnects between data center racks and blade servers, delivering minimal latency and bit rates of 400Gb/s per lane. Optical IM/DD links powered by electro-absorption modulators (EAMs) are emerging as a key enabler.

imec has formed a 110GHz-plus C-band GeSi EAM on its 300mm SiPh platform

“Developing the right modulators to support these optical IM/DD links has been a major research focus, as commonly-used technology options all have drawbacks,” said Cedric Bruynsteen, a researcher at IDLab, an imec research group at Ghent University, Belgium.

“Thin-film lithium niobate Mach-Zehnder modulators, for instance, offer excellent linearity, low optical loss, and very high bandwidth, but their large footprint and contamination challenges hinder wafer-scale integration with advanced CMOS logic, challenging their use for future co-packaged optics and optical I/O. Micro-ring modulators, on the other hand, provide high integration density but require substantial stabilization control circuitry, which limits their energy efficiency,” he said.

“Our C-band GeSi EAM addresses these challenges head-on. By exploiting the Franz-Keldysh effect, it achieves compactness, high speed, and low power consumption. And thanks to its GeSi foundation, it integrates seamlessly on our 300mm silicon photonics platform – enabling mass-market manufacturability,” Bruynsteen added.

‘Two world firsts’

imec says its achievement combines two world firsts: the first demonstration of a beyond-110GHz GeSi EAM operating in the C-band, and the first realization of a net 400Gb/s per-lane transmission with any silicon-based EAM.

On the device integration side, imec researchers have optimized footprint dimensions, doping schemes and epitaxial growth processes. On the system side, they have developed a robust transmission setup that showcased the EAM’s capability for a net 400Gb/s per-lane data transmission, operating in a PAM-4 IM/DD link.

“These results clearly illustrate the potential of our GeSi EAM to enable next-generation, scale-up optical interconnects. Interestingly, however, the modulator itself was never the limiting factor in our bandwidth experiments – it was the measurement equipment that capped us at 110GHz. The next step is to uncover the device’s true bandwidth limits and evaluate its performance under higher temperatures representative of data center conditions,” concluded Bruynsteen.

In parallel, imec is making the GeSi EAM available to partners, enabling them to explore its potential for scale-up networks inside AI training clusters.

Photon Bridge platform demoed with PIC for PON transceivers
Photon Bridge, a developer of photonic integration, has announced a collaboration with transceiver developer PICadvanced to present prototype transceivers built using its novel multi-material integrated photonics platform. Highlighted at ECOC 2025, in Copenhagen, the prototypes represent one of the first customer engagements using Photon Bridge’s breakthrough cantilever waveguide coupling technology, underscoring both technology maturity and early market traction.

In collaboration with PICadvanced, Photon Bridge’s photonic integrated circuit (PIC)—incorporating a tunable laser, modulators, and receive path—has been integrated into prototype pluggable transceivers targeting the passive optical networks market.

PICadvanced compact PON transceiver built with a Photon Bridge PIC

“We founded Photon Bridge to redefine photonic integration, and these prototypes with PICadvanced are a major validation of our technology and vision,” said Rui Santos, CTO and co-founder of Photon Bridge. “By combining III-V performance with silicon scalability, we’re enabling smaller, more powerful, and cost-effective transceivers that meet the growing bandwidth demands of telecom and AI systems.”

“Photon Bridge’s technology provides the integration density and performance required to advance the next generation of PON transceivers,” said António Teixeira, CSTO of PICadvanced. “We’re excited to be among the first to prototype this innovation, strengthening our ability to deliver cutting-edge solutions to our customers.”

Source: optics.org