Vacancy: Nano-ridge lasers emitting at 1300 nm (Open)

Context

Recently, a team consisting of several IMEC groups and the Photonics Research Group at Ghent University demonstrated a unique approach for realizing an electrically injected laser on a Silicon Photonics platform. These results were published in Nature [1] and received attention world-wide as it might solve one of the last remaining bottlenecks hindering a complete breakthrough of Silicon Photonic integrated circuits.
Silicon Photonics has matured rapidly in the last decade but given silicon's indirect bandgap it remains challenging to integrate efficient lasers directly on the platform. III-V semiconductors do allow for efficient laser emission but exhibit an important lattice constant mismatch with silicon, complicating their integration. The IMEC epitaxy team circumvented this problem by growing the material in narrow trenches within a silicon oxide layer deposited on the silicon substrate to suppress defects. Once extending above the mask, these so-called nano-ridges are expanded, forming a low loss waveguide. Together with an innovative contacting method, this allowed us to demonstrate lasers with low threshold current, fully fabricated in imec's 300mm pilot line.
While showing promising performance, the current lasers operate at a wavelength around 1050 nm. For practical applications, a wavelength around 1300 nm (as now commonly for interconnect applications, e.g. in data centers) is much more relevant. Another challenge remains the integration with silicon waveguides. To tackle this problem, we set up a project with the Ghent University Photonics Research Group, IMEC and Philipps University Marburg, with the aim of investigating new gain materials based on GaAs that emit at 1300 nm. The project will first explore the growth of various gain materials in a lab environment to ensure fast progress and feedback. The material that shows the most promise based on structural and optical characterization will then be used to fabricate devices for lasing demonstration. The growth of the best gain material will then be transferred to the CMOS fab for the deposition and complete device fabrication on 300 mm Si, making the CMOS-compatible III-V laser ready to be integrated into a Si photonics platform.

Job Description

The task of the Photonics Research Group within the project and hence your task as PhD student relates on the one hand to the characterization of the novel materials that will be developed by the project partners and on the other hand to the proposal of new laser concepts that allow for low threshold single mode lasing and coupling to silicon mode waveguides. Following an initial screening using spectroscopic techniques, you will fabricate proof of principle devices and evaluate their performance. The most successful approaches will then be transferred to the 300 mm fab. The proof-of-principle devices will initially be based on existing device concepts, but in parallel you will also work on improving the laser design and evaluate, through design and modelling, some novel device concepts. You will also study the integration with silicon waveguides, which has thus far not been demonstrated experimentally.

Candidate Profile

You have a master in Photonics, Applied Physics, Microelectronics or similar. You are willing to combine simulation and design, cleanroom fabrication and characterisation

How to apply?

Send your CV and motivation letter to dries.vanthourhout@ugent.be before June 15th, 2025

More information

• Contact: Dries Van Thourhout
• [1] Y. De Koninck et al., GaAs nano-ridge laser diodes fully fabricated in a 300-mm CMOS pilot line, Nature, vol. 637, no. 8044, Jan. 2025, doi: 10.1038/s41586-024-08364-2
• Same paper on arXiv

Related research topics

• IIIV microlasers epitaxially grown on silicon