Smaller Scales, Bigger Power: an Interview with Dr. Stuart MacFarquhar, Laureate of the Photonics100 2025 Award
With the advent of advanced data processing for emerging technologies such as AI or 6G, the pressure is on for scientists to come up with accommodating solutions. People demand reliable, fast and cost-effective innovations at an unprecedented scale to facilitate next-gen data management breakthroughs. Dr. Stuart MacFarquhar is precisely one of those standing on the precipice of scientific trial and error, working on the latest design developments in Photonics Integrated Circuits (PICs) – a piece of technology whose evolution will disrupt everything from quantum computing to how we treat diabetes. As a Design Engineer at G&H, his efforts have been recognized in the latest Photonics 100 round-up, an award that sums up the world’s leading talent in optics and photonics. We sat down with Stuart to understand what is so exciting about the emergence of next-gen PICs, what role he is playing in moving this technology forward and how he feels about winning such a prestigious accolade from ElectroOptics.
Q: Stuart, congratulations on being added to the Photonics 100 2025 list! How does it feel to receive this award?
SM: Thank you, I haven't worked it out yet if I'm being perfectly honest. The announcement has landed as a surprise and at a point where I am fully immersed in some demanding, yet truly interesting projects within our Photonics division at G&H. I believe being recognized at this level is a very nice feeling to experience. Especially given the other names on the Photonics100 list for 2025, I am truly humbled and grateful for this public appreciation.
Q: Tell us more about the award – what was it for?
SM: My current field of research is Photonic Integrated Circuits. Basically, they are a way to manipulate light via a microchip, a technology which opens up a vast array of applications because of their reliability, scalability and high-volume cost effectiveness. At G&H, we wanted to firstly create our own PIC designs and test out these different strategies, to see what can be made possible with them. At the moment, we’re busy with micro-transfer printing for heterogeneous photonic integrated circuits in collaboration with strategic EU-based partners. We know the concept is fairly widespread in certain R&D circles, but what we are trying to do is to prove its commercial viability, too.
Q: Why is this process challenging to achieve?
SM: Like everything PIC-related, alignment is one of the biggest challenges we face when making a functional system. Compared to the fiber-optics that we’re used to, there’s almost no room for error, in some cases losing half the light if we’re off by less than 1/1000th of a mm. This means that the selection and placement have to be done with extreme accuracy, but also high speed to avoid disrupting the high-volume manufacture.
Q:Working on PICs, what demand are you answering with this emerging technology?
SM: Photonic integrated circuits answer a variety of market needs. It’s truly a Leonardo da Vinci type of innovations. Specifically for photonics, one of the underlying trends is the push for miniaturization, making things smaller or making them fit in smaller spaces. The scale of this process includes reducing size, weight and power for devices and subsystems. In the case of the research and development we’re handling, my angle has been to reimagine an optical circuit design that currently fits in something the size of matchbox-to fingernail-size, meaning a 5x3 cm to 5x5 mm conversion roughly, with enhanced functionality. Silicon-based photonics is currently considered as one of the class stars for different implementations, particularly regarding high circuit complexity models, which is what we are working with at the moment. Plus, coming back to the micro-transfer printing idea, that process helps us optimize the reliability of the micro- and nano-sized solutions. By working on this big-picture process, we are paving way for a solid manner of element bonding, done in a very precise manner. We're trying to develop a methodology where you create your optical circuitry on the silicon nitride wafers as you would for any other process. And then, the point would be to independently create all of your lasers, detectors and so on, on their own native substrate materials to optimize them properly. What this means is that you can come in with a separate and carefully designed stamp that uses very, very minor adhesion forces. And then, you apply just enough pressure to cause adhesion on the laser block, together with breakage on the tethers on the new design. The logic behind this process is that by carefully adjusting the shape and positioning of the stamp, you can achieve the material transfer that you want, potentially endlessly in theory. This is something that is currently being investigated in photonics and we are making great progress on this at G&H. We want to elevate those branches that are being powered by photonic integrated circuits by offering more time-effective manufacturing options.
Q: What are some examples of those branches that are about to be overhauled by this optimized technology?
SM: Oh, there are all sorts of interesting things you can do in integrated photonics. There are companies interested in developing, for example, a fully implantable diagnostic sensor fora diabetes monitor.It’s the first thing that came to mind. As long as your entire device is in biologically safe and you use materials that can be implanted into the body, you could take a sort of 5-millimetre by 5-millimetre chip, surgically implant it somewhere where there is blood flow and have constant data input about your blood sugar level.Compared to the more intermittent and invasive way people are checking that data today, this emerging solution means that you don't have to take a blood sample every time you feel wobbly. You don’t even need to get to that wobbly stage in the first place. That translates into a massive life improvement which could be available to the 422 million people who have been diagnosed with diabetes around the world, according to the World Health Organization. Especially now that we have the capability to merge photonics know-how with life sciences acumen within the G&H group, such applications are becoming more of a possibility than ever before.
Q: That is incredible. Thank you, Stuart, for your time and thought-provoking insights.
SM: Thank you as well for this space, and again, thank you to everyone involved in putting together such a prestigious, community-building list for photonics like the Photonics 100. I am humbled by this honor.