Thermal Management of Hybrid Integrated Lasers in Si Photonics

(28:25 + Q&A) Dr. David Coenen, imec
From the 2024 IEEE Symposium on Reliability for Electronics and Photonics Packaging
Summary: Silicon photonics is becoming a mainstream technology in telecom and datacom for efficient, high bandwidth and reliable I/O. With the advent of large AI models such as LLMs, HPC systems in data centers are becoming constrained by the energy cost of moving data between memory and compute units. Co-packaged optical transceivers can alleviate this bottleneck by minimizing the physical distance between the network switch and transceivers. A new challenge arises with these highly integrated electronic-photonic systems: as packages become more compact and highly integrated, power densities rise, and thermal management is further complicated. With this backdrop, this talk will focus on thermal management of hybrid integrated lasers, which are a key component in photonic integrated circuits.
Lasers are essential in optical systems for providing an on-chip light source. The byproduct of the generated light is heat, which negatively impacts the laser performance: lasing efficiency, threshold current and laser reliability. Furthermore, packaging multiple laser close to each other causes thermal crosstalk. For these reasons, laser thermal management is imperative for efficient and reliable system performance. First, laser thermal characterization will be discussed. Following this, different strategies for improving laser thermal performance will be discussed. These include adapting the laser – carrier interface, applying underfill, top side heat sink attachment and thermo-electric cooling. Finally, the thermal modelling of large laser arrays will be discussed, where thermal crosstalk becomes a dominant effect. Non-linear coupling between the optical- and thermal system of equations reveals surprising laser array layout optimization results.
Bio: David Coenen obtained M.Sc. degrees in aerospace engineering (2018) and mechanical energy engineering (2020) from KU Leuven and Ghent University, respectively. He obtained a Ph.D. in materials engineering from KU Leuven in 2023, focussing on thermal management of Si photonic optical transceivers. He is currently a senior researcher at imec, with research interests in Si photonics, advanced cooling solutions and machine learning algorithms applied to thermal analysis.

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