Scientists develop new technique for wafer-scale testing of photonic integrated circuits

Researchers from Southampton and Bordeaux have unveiled a new technique for the industrial testing of photonics chips, an important step in the realisation of an emerging multi-billion pound industry.

The international research, presented this month in the Nature Communications journal, brings together advanced theoretical modelling and precise experimental studies to develop a quantitative understanding of how light travels through a chip.

Photonic integrated circuits, the technology of using light on a chip, is a rapidly developing industry with applications in data communication and optical interconnects.

Whereas electronic testing of circuits is a mature field, capabilities are still lacking for photonic circuits and not well-suited to industrial-scale testing. There is therefore a strong need to develop advanced probes capable of testing fabricated devices remotely and with high throughput.

Researchers from the Department of Physics and Astronomy at the University of Southampton and the Laboratory for Photonics, Numerics and Nanosciences (LP2N) in Bordeaux, France, have demonstrated the new technique which uses a pulsed laser to divert and then measure the flow of light through a device.

The theory used to interpret these results applies to many photonic systems with great accuracy and minimal computational cost. Comparisons between the experimentally obtained and modelled maps for the devices showed agreement as high as 95%, a clear indication of the robustness of the model and of the experimental technique.

Professor Otto Muskens,, from Southampton’s Integrated Nanophotonics Group and Principal Investigator of the study, says: "Our new technique will be of interest for photonics industry and we are actively looking for end users to test our methods in real-world applications. Further development will be needed to explore the integration of the technique into actual probe stations used by industry, ultimately merging optical and electronic testing onto one single platform.”

The work was supported by the UK Silicon Photonics for Future Systems research programme and involved Southampton’s state-of-the-art cleanroom facilities and the Silicon Photonics research group led by Professor Graham Reed.