imec demonstrated a germanium-silicon (GeSi) electro-absorption modulator (EAM) capable of operating past 110 GHz. Fabricated on its 300-mm GeSi wafers (see image above), the EAM achieves a net data rate of 400 Gb/s per lane in an extremely compact form factor for miniaturized applications.
The energy efficiency and fast communication rates of the EAM are a good fit for the demands of artificial intelligence (AI) and machine learning (ML) across diverse markets. It's expected to be a powerful addition to systems employing optical intensity modulation with direct detection (IM/DD) for short-distance, rapid transfers of copious quantities of data within commercial, industrial, and military systems.
Cedric Bruynsteen, a researcher at the IDLab imec research group at Ghent University (Ghent, Belgium), explained, “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.”
He noted some of the problems with current technology, “Thin-film lithium-niobate Mach-Zehnder modulators (MZMs), 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.”
Bruynsteen added that energy efficiency is a further reason to pursue GeSi EAMs. “Micro-ring modulators, on the other hand, provide high integration density but require substantial stabilization control circuitry, which limits their energy efficiency.”
He pointed out the value of the GeSi devices: “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 300-mm silicon photonics platform — enabling mass-market manufacturability.”
Despite being produced in high volumes, imec’s GeSi EAMs perform well enough to support the highest-speed optical interconnections over short distances for efficient processing of large-scale data.
