Understanding High Optical Power Induced Degradation Mechanisms in Si Photonic Devices

Advances in cloud computing, artificial intelligence training, and high-performance computing systems demand high data transmission rates. To resolve this, optical interconnects are pushed from long-distance data communications towards short-distance, high-speed links between servers/racks in and across data centers. The key enabler is silicon photonics (SiPho), which leverages mature silicon-based semiconductor manufacturing platforms to integrate optical components into a photonic integrated circuit (PIC).

In short-reach, high-speed links in data centers, SiPho devices transmit/receive light from high-power laser sources. The high optical power can cause self-heating, collapse electric fields, and even induce long-term reliability issues, ultimately resulting in a PIC failure. The degradation of device performance over time is linked to defects, either pre-existing after fabrication or generated under optoelectrical stress. The properties of these defects, their interactions with electrons/photons, and their impact on device optoelectronic properties are critical and thus require further investigation.

In 2026, a new industrial qualification standard for SiPho was released [1], stating that a photodiode must pass a high-optical-power stress test to ensure the device can maintain its function over the required lifetime. However, there is hardly any fundamental research on how SiPho devices degrade under high optical power.

The purpose of this PhD topic, therefore, is to systematically investigate the fundamental degradation physics and related defect kinetics of SiPho devices under high optical power. The devices of interest will be emerging high-speed modulators and photodiodes.

[1] Silicon Photonics Qualification and Reliability Requirements | IEEETV

What will you do:

• Perform in-depth electro-optical characterization to study degradation behaviors and develop new failure-mechanism-oriented test sequences, where necessary.
• Conduct systematic analyses to better understand the underlying reliability physics.
• Develop physics-based opto-electrical models to describe experimental data, which will enable accurate prediction of device lifetime at operating conditions.
• Use advanced material analysis techniques to validate degradation mechanisms.
• Continuously discuss with reliability, device, and process engineers, and work closely with imec’s industrial partners worldwide.
• Publish your work in high-impact journals and present it at international conferences.