While other children read Harry Potter or adventure books, Michael Kissner was particularly taken with the programming book Code by Charles Petzold. He knew early on that he would like to build a processor himself one day, even if he never had an optical processor in mind at the time. He didn't take the 1990s series Stargate seriously: There, all the alien processors were crystals working with light. What nonsense. Just science fiction - until Microsoft announced at the end of 2019 that it had stored data in quartz glass, a crystal. Immediately, the old enthusiasm was sparked, and Michael Kissner, who had by then studied mathematical engineering and mathematical physics as well as earned a doctorate in artificial intelligence, used the pandemic to finally delve into his childhood dream.

There have been many approaches to optical computing over the past 40 years, reports Kissner, who most recently worked in cybersecurity, but the approaches were just too bottom-up. I, on the other hand, was pondering: That is what an optical processor has to be able to do in the end. And if it has to be able to do that, then that's what the transistor has to look like, and then I need these physical effects. Only then did I start looking for an optical transistor that could fulfill that. That's also how Kissner came across his co-founder, Dr. Leonardo del Bino. I read hundreds of papers on optical transistor designs. The one that fit perfectly was Leonardo's.

Light interacts only reluctantly with light. It's much easier to process data via electrons that repel each other - but there are always high losses due to resistance, continues Kissner passionately, who first moved to Germany at 18 and grew up in Iran, Indonesia and Singapore. Even humans absorb over 80 percent of all information with their eyes. The information density is infinitely greater with light.

At its core, the approach is based on the idea of using optical nodes as logic circuits. The information we process is available in the form of light. We process light without converting it to an electronic signal and back again, del Bino, a native Italian, described. Our processor can be integrated into any application, but at the outset it is particularly useful for devices that receive and transmit information in the form of light, for example, for routers and switches in networks. Getting light to interact with light efficiently is the crucial point. It does work in theory - now it's time to put it to the test in practice and build prototypes. A light processor saves a huge amount of energy and can process much more data much faster, with no latency due to conversion, del Bino explains. As a result, he says, power and cooling requirements are reduced enormously compared to conventional processors.

Environmental friendliness is a key driver for the founders in the first place. Electronic processors, for example, consume immense amounts of ultra-pure water for purging in the manufacturing process. The optical version, on the other hand, doesn't have as many process steps, is more robust and requires much less water. We want to offer an alternative that is more sustainable; we won't be the smallest to do that. What's more, the technology can be manufactured in Europe: We are planning chips on the order of 130 nanometers; there are already tens of factories here for this, reports Leonardo del Bino, specialized in materials science and nonlinear photonics.