Interdisciplinary Physics and Astronomy research at Southampton have been awarded more than £700,000 Engineering and Physical Sciences Research Council (EPSRC) funding to develop new instruments that can improve environmental sustainability when testing photonic integrated circuits at full wafer scale.

Professor Otto Muskens, Professor of Physics and Head of the Quantum Light and Matter Group, is leading the project that will involve colleagues from the Zepler Institute's (ZI) Silicon Photonics Group and Cornerstone silicon photonics rapid prototyping foundry.

Otto said: “Integrated photonics is becoming a multi-billion-pound industry that is revolutionising information and communication technology. High volume fabrication of circuits with reliable performance requires sophisticated testing methods that can identify any malfunctioning devices early in the process.”

“On-wafer testing reduces unnecessary waste in materials, tooling and energy and feeds information on tolerances back into the manufacturing process. Cleanrooms are amongst the most energy and carbon intensive industries and advanced testing methods can contribute to an improved environmental sustainability.”

“Our new techniques are complementary to existing wafer probers, which only measure end-to-end performance of the device, and allow us to look inside the circuit to obtain information on the individual component of the device.”

“We have been working on the fundamental science of this research for a number of years and have developed the technique to a laboratory prototype that has been successfully used in basic research in our group.”

“Everything was ready for a full-scale development - we had already developed the collaborations with industrial partners and foundries - and this EPSRC funding allows us to now convert all this work into a real project. Our aim is to develop tools that will improve manufacturing research and can initially be used in the characterisation of devices coming out of research labs. However, longer term our ambition is to develop this into a tool than can be used in industry itself.”

As well as working with colleagues in the ZI and at Cornerstone, the team will also collaborate with Smart Photonics in The Netherlands, IHP Microelectronics, in Germany, and the MISSION Program Grant that is aimed at developing a mid-infrared integrated photonics platform for sensing.

Otto added: “For many years we have been looking at using these tools for basic research, it is an exciting challenge for us to be able to develop something that could find much wider use. We are using this opportunity to develop new skills in our lab, which may then be used for other parts of our research.”

“We expect that new and interesting things will appear when we are looking at the range of devices and that there will be plenty of scope of new collaborations and multidisciplinary research.”

Southampton research helps to challenge the cause of halting star formation in massive galaxies

Massive galaxies could actually generate a sudden increase in star formation just before they shut down completely, according to new research by a team of astronomers including researchers from Physics and Astronomy at Southampton.

Until now, most data have shown clear evidence that star formation in galaxies steadily declines with time. The cause of this halting star formation is an ongoing and continuously debated mystery.

Now the new research conducted by Southampton, the Institute of Astrophysics of the Canary Islands and the Institute of Space Sciences, has revealed that galaxies with active cores may undergo a period of rapid star birth before they take their last breaths. The findings have been published in the Monthly Notices of the Royal Astronomical Society: Letters.

Professor Francesco Shankar, Professor of Astrophysics, who was involved in the research said: "Local galaxies are observed to gradually reduce the rate in which they are forming stars, but our data suggest that supermassive black holes are not the major culprit here. They may contribute to quenching star formation, but the quest is still open."

Most, if not all, massive galaxies are believed to harbour supermassive black holes at their centres. When supermassive black holes are actively accreting gas, they can radiate as much energy as the galaxy in which they reside. The popular picture is that powerful winds and jets produced by the central Active Galactic Nucleus (AGN) are able to expel or heat gas within the host galaxy, removing the material needed to make stars.

However, the study suggests that galaxies with an AGN hosting continuously growing black holes that emit large amounts of energy and radiation have temporarily increased the rate at which they form stars by accumulating fresh gas from their surroundings.

Equipped with a large sample of more than three thousand nearby galaxies hosting an AGN, the team used new data analysis techniques to measure how the star formation of the galaxies has changed over cosmic time.

Challenging the expectations from the standard scenario, the team found that nearby galaxies hosting AGN are not simply gradually quenching their star forming rate. On the contrary, they are going through a "rejuvenation phase" most of the galaxies in the sample with active black holes show clear signatures of a rising not declining star formation rate in recent epochs.

The team concluded that current AGN activity may be contributing to, but not causing, the observed quenching of star birth. Therefore, the rejuvenation of galaxies with active nuclei may be the "last breaths" in the lives of galaxies, before they completely stop forming new stars.

Francesco is a theoretical astronomer renowned for his work focused on the statistical description of the cosmological evolution of supermassive black holes. He contributed to the present research suggesting new analyses of different data sets and then guiding the interpretation of the results.