Imec debuts 100 GHz Ge/Si avalanche photodiode at ECOC 2026

Technologies and Products

Semiconductor manufacturer Imec has launched a new Ge/Si photodiode that can handle fast signals, works at low power, and deliver high sensitivity across key-fibre optic wavelengths at ECOC 2026.

This breakthrough marks an important step toward next-generation optical interconnects for AI data centres, where vast amounts of data must be exchanged with ever-higher speed and energy efficiency, says the company.

A Ge/Si (germanium-on-silicon) is a high-speed semiconductor sensor that converts faint light signals into electrical signals with built-in internal amplification

Imec’s Ge/Si avalanche photodiode combines 100 GHz bandwidth, low-voltage (5 V) operation and a responsivity of 1.8 A/W across both the O- and C-bands.

“The team started from the well-established SACM (separate absorption, charge and multiplication) APD architecture, but re-engineered the device at its core,” said Joris Van Campenhout, VP R&D Optical Interconnects at imec. “By scaling the multiplication layer width to below 100 nm – leveraging a deeply-recessed germanium-in-silicon structure – and eliminating the charge layer, we were able to simultaneously achieve 100 GHz bandwidth, 5 V operation and a responsivity of 1.8 A/W, corresponding to approximately a twofold internal gain.”

“An additional advantage is that the device delivers comparable performance in both the O-band and C-band, giving system architects greater flexibility when designing future optical interconnects,” Van Campenhout added.

To demonstrate the technology’s system-level potential, imec combined its APD with the beyond-110 GHz C-band Ge/Si EAM it unveiled at last year’s ECOC. Together, the devices were used to demonstrate the first net 400 Gbps optical link employing an APD.

“Delivering a 3 dB receiver-sensitivity improvement, the APD provides additional link margin compared with a conventional photodiode,” said Van Campenhout. “Depending on system requirements, this margin can be used either to reduce laser power consumption or to accommodate higher optical losses. Combined with its high bandwidth and low operating voltage, this makes the device particularly attractive for future scale-up optical interconnects.”