Everything is fractal — an interview with Ruth Houbertz

With more than 120 patents, a collection of personal awards and many prizes for her spin-off company specializing in 3D laser lithography, Dr. Ruth Houbertz likes to be on the move, whether in her role as a scientist, company founder, activist or motorcyclist. A successful tech founder and mother, she is a role model and a strong personality with iron-clad principles. She left a position at Sandia National Laboratories in the United States to move to Fraunhofer ISC in Würzburg, where she worked for 14 years. During her time there, she initiated several restructuring measures to strengthen her team’s profile, and ulti-mately merged the optics and electronics divisions. This was a success: She developed a process that uses an optical waveguide to con-nect a vertical-cavity surface-emitting laser (VCSEL) directly to a photodiode, which won her the Joseph von Fraunhofer Prize in 2007. Her team used two-photon absorp-tion (TPA) to shape a material developed at Fraunhofer ISC into three-dimensional structures. Houbertz has continued to develop this process, and in 2013 she trans-ferred it to the spin-off Multiphoton Optics GmbH. As an entrepreneur, she has big plans for the startup, for which she has received numerous accolades and prizes. She sold it in early 2021. Today, Houbertz works with ThinkMade Engineering & Consulting as an advisor to businesses for innovation and technology issues and with SprinD as an innovation manager, as well as being an active member of many committees and trade associa-tions. Her project “Society6.0” is helping to set new standards in education and in-formation for all, part of this native Rhinelander’s commitment to creating a sustaina-ble, responsible society in which nobody is left behind.

Ruth Houbertz
© Fraunhofer ISC
Ruth Houbertz can look back on a handsome collection of awards as a scientist and as an entrepreneur.
»Nicht jammern, sondern tun!«
© Houbertz
"Don't Complain, Do!" - That's how Ruth Houbertz, who lives in Würzburg by choice, sums up the idea behind her new project "Society6.0 Movement for People and the Environment. It is a network for a sustainable and responsible society and this cooperative addresses all topics from economy, technology and social issues. This group is open to everyone and through it everyone should be empowered to develop their own strengths and use them for themselves and others.
Das von Ruth Houbertz maßgeblich entwickelte Verfahren ermöglicht sehr kleine und hochpräzise Bauteile, wie etwa in diesem Beispiel optische Bauteile.
© Multiphonton Optics
The process, which was significantly developed by Ruth Houbertz, enables very small and high-precision objects with complex structures, such as optical components in this example.

Dr. Houbertz, you gave up a secure job at Fraunhofer to pursue the adventure of founding a startup.

I took a chance with the spin-off because I was, and still am, convinced that optical data transfer can solve at least part of the energy problems in data centers. Optical components are capable of transferring each bit of data using a fraction of the energy of an electronic transfer. But there are also many other areas where optical processes can be put to use. For example, smartphones have tiny optical components built into them which can be made even smaller using 3D lithography. The process can also be used to produce ultra-thin optical components with additional functions — a kind of meta-optics. I personally really like this idea, but it’s just one of many examples of ambitious concepts that have plenty of leverage to revolutionize the way we build optics today.

So there are more consumer product implementations still to come?

You can’t look at these things in isolation. These are systems that have to work to-gether, and optical components are no use on their own because there are always interfaces where optical signals need to be converted into electrical information. On top of that, it’s only been two decades since we started integrating optical data trans-fer into a microelectronic world, compared to over 70 years of development in the field of microelectronics. The market forecasts predicted that 2018 would be the year when optical technologies would “take off” — that’s what we’re seeing now, only a couple of years behind schedule.

Could you briefly explain the process you’ve developed?

If you pour pancake batter into a pan with some hot and some cold areas, you’ll see a pattern: the batter in the hot areas will cook and harden, and the rest will remain liquid and get poured away. Conventional lithography works in a similar way, using an exposure process with a particular wavelength (or color) of light and a mask contain-ing the structures we want to produce. That’s how we make microelectronic compo-nents like microchips, for example. We can use a liquid that solidifies when exposed to light, and apply a solvent to remove the unexposed material — this process is de-scribed as “additive.” Conversely, we can also use light exposure to break down solid bonds so we can remove certain pieces — this process is “subtractive.” What’s special about the process I’ve developed is that it doesn’t even need a mask; it uses a material that I refined as part of my work on this technology at the Fraunhofer-Gesellschaft. The light can be directed through this material like ink through a pen, meaning that it has complete freedom of movement. This is what clearly sets us apart from the com-petition. However, the process can also build a three-dimensional structure layer by layer, like with a 3D printer, which is the most common form of structuring. This pro-duces a precision-made 3D structure. What’s unique about Multiphoton Optics is the ability to orchestrate additive and subtractive processes so that complex structures can be constructed and deconstructed in a single machine. That’s why I’ve dedicated around 20 years of my life to the study of light-matter interactions and worked inten-sively with software and control systems.

You’ve collected not only personal awards, but also a number of prestigious prizes for the company you founded, and yet in the spring you agreed to sell it.

Prizes aren’t everything. I actually wanted to turn this company into a unicorn [a startup with a valuation of over a billion dollars], but since then I’ve come to the con-clusion that, apart from Fraunhofer, the investors never understood that chasing a quick buck is not the way to achieve great things. It’s never good to base decisions on fear. With Heidelberg Instruments Microtechnology my startup is in very capable hands, but I would have liked to see for myself the company’s rapid development into worthwhile fields of application. My dream, which I haven’t given up on yet despite the sale of my company, is to reach a new dimension of optical packaging for co-packaged on-board optics and wafer-scale optics with a level of freedom that just isn’t possible with the processes in use today. That would open up completely new possibil-ities: super-thin, extremely light, highly integrable optics. As with everything, though, there’s no black and white, or — in technological terms — good and bad technology. The real art lies in combining technologies and hybrid approaches.

Did personal reasons also factor into the sale?

There’s one thing I can be sure of: If I ever write my memoir, it will start and end with the words, “Stay true to yourself and be passionate and authentic!” If I don’t love what I’m doing, if it’s not fun or if it’s not taking me any further, I leave. That’s how I’ve always done things, even at school. Whenever I’d start to get bored with class, I used to climb out of the window and walk to the market in Aachen to watch and meet other people. To me, that was a much more useful way to spend my time. Whether I’m founding a company or baking with my kids, I only ever do things I believe in and enjoy. We should never compromise ourselves.

So you’re never willing to compromise?

In general, I’m prepared to reach compromises. A harmonious environment is important to me, and that means sometimes you need to go with the flow. The key thing, though, is to ask yourself what you ultimately want to achieve for everyone. I’m a fan of win-win situations, and I will be for the rest of my life. Of course, there’s always the risk of compromising yourself, but that can be avoided through careful reflection. I think Steve Jobs was an admirable example of someone who wouldn’t budge from his principles. If I don’t feel like I’m in the right place, I change the parameters of the job or leave completely. There’s no point making myself unhappy by being around people with no backbone or scientific honesty. Sometimes it takes a little longer for me because I put feeling and emotion into everything I do. Ultimately, though, I’m taking this chance because every change in life takes us to a new level, usually a much better one than the last. We have the choice to keep an open mind and turn negatives into positives.

There were times in my professional life when I felt like I was losing my identity — as I always say in mentoring programs or podium discussions, if you notice that happening, leave! Change something! Even though it can be hard sometimes. After all, I didn’t know if my independent career or the Society6.0 project would work. After the sale, I actually got a very lucrative job offer from the US. I want my own life and not to have to do what other people expect of me, though, so I decided to turn it down. For me, creativity only happens when I can think freely. Because of that, I chose uncertainty again, even though it was a tempting prospect to work in a cutting-edge major corporation.





Ruth Houbertz mit Motorrad
© Privat
"To free her mind," Ruth Houbertz likes to go for a spin on her motorcycle.


How did you end up at Fraunhofer?



After working at Sandia National Laboratories in the US, I joined Fraunhofer ISC as a research associate. I soon had my very first team, initially called the microsystems engineering team, which later became hybrid polymers for microsystems engineering. At the time, many scientists were conducting research into interesting materials and a plethora of applications in fields like microelectronics, optics, battery development, medicine and latent heat storage — this was all really exciting, but our challenge was to make a serious enterprise out of it. So I started to cluster and refine these amazing activities, similarly to founding a startup, and then began outsourcing them to other existing and new divisions within the institute. This allowed to me to focus more on the combination of optics and electronics and to do what I enjoy the most: helping things take off and then handing them over to others. I don’t find sheer volume especially challenging — there are others who are better at it than I am and who identify with it more than I’m prepared to.


Consolidating the division took me 10 or 11 years. At the end of it, the division was just called “Optics and Electronics,” but it also covered materials and technologies for those areas of application, industries and markets, and we had a lot of success with those, too. At the same time, I was also working on developing 3D lithography and multiphoton polymerization on top of my full-time management job. A lot of that ended up happening during weekends and public holidays and in the evenings. It was hard work, but I loved it.

Had you already had the idea for the spin-off by then?


The idea for the spin-off started back in 2007. That was the year that I strategically presented the spin-off idea to my planning committee for the first time. Together with our client at the time, the Austrian circuit board manufacturer AT&S AG, I looked for potential system builders whose systems we could use for prototype and pilot production in the circuit board environment. We spoke to a few candidates — including Nanoscribe GmbH, which would later become a competitor of Multiphoton Optics, in early 2008 — but they didn’t want to build the system we were asking for. The idea was to buy a system so that I could work with a team to develop a process that we could scale very quickly. To be absolutely clear, in 2007 and 2008 we already had six channels offering data transfer rates of around 42 Gbit/s with a bit error ratio of 10-9. I received the Joseph von Fraunhofer Prize and then, in 2013, the SPIE Green Photonics Award in the United States for those developments, together with a graduate student and a doctoral student. That was wild! These days we have better components that allow higher data transfer rates; if we’d had those then, I’m certain we could easily have achieved much more. It’s worth stressing that, to me, 800G isn’t about the technologies developed by me and my teams. It’s about the availability of components that can do the job, and about the willingness of clients to do something different and integrate things that aren’t part of their conventional processes. Where would microelectronics be today if nobody had done things differently back then? The spin-off happened because we first needed the hardware and software to provide the conditions that would allow us to use the fruits of our labor in the form of innovative kinds of applications and products. Engineers should be able to use the hardware similarly to the way they would use a mask writer.



With the team you were given to lead, you managed to produce astounding developments. Multiphoton Optics was very successful, and that was a relatively small team, too. What’s your leadership secret?


To me, small, highly flexible teams are the key. It’s really important for there to be a sense of fun and creativity, but also pragmatism. I’ve seen many great people who’ve been frustrated in some way and have lost their sense of joy in what they were doing. Though I place high demands on myself, too, because I think we reach our goals faster that way. It’s important to be able to put yourself in your team members’ shoes, and it’s essential to understand how much time you need for a project so you don’t set unrealistic expectations. At the same time, the expectations should still be very high, because that way you reach your goals faster and keep things interesting. Management decisions can often seem unfair, but if you explain your approach, it’s much easier to keep your team on the same page. Conversely, I’ve always tried to put myself in my superiors’ shoes and understand their decisions, especially during my time at Fraunhofer.


Progress and innovation shouldn’t be impeded or slowed down by administrative barriers. There are a lot of regulations that make sense in one place but cause an obstruction somewhere else. As a manager, though, you can always prioritize. I was often confronted with problems like that at the start of my Fraunhofer career. My boss at the time always said to me, “You can do it!” Because of that, I always took on responsibilities for bigger jobs that I shouldn’t really have had based on my position at the time. What I’m trying to say is that it’s a question of willingness to take on responsibility, and a little anarchism won’t do any harm! A lot of managers or aren’t able or willing to take on responsibility. That’s why we need relaxed managers who can make occasional mistakes without being humiliated in front of everyone. That’s happened to me before — and I’m not the only one — but it can have a really positive effect, too, if you stay true to yourself. Ultimately, I just feel sorry for people who act like that.  


What did you find special about Fraunhofer?


There’s a lot of freedom here to do things without having to go all the way up the chain of command, which makes things much faster and more efficient. That means it’s very easy to fend off people who get in the way by trying to take advantage as soon as something becomes successful. There are always enough flexible and creative people at Fraunhofer. Fraunhofer provides a lot of scientific freedom, although sometimes you need to actively take it or earn it. In fact, the institute management supported me and actually encouraged the spin-off, even in the face of some internal resistance. It’s important to understand that Fraunhofer needs to undergo a technology transfer and that it won’t be able simply to continue incubating technologies without putting them into practice. Fraunhofer also provides a lot of freedom to women and families, although once again you need to actively accept the freedom on offer.


 Fraunhofer ISC was more than an employer to me — it was a kind of haven. I got to know so many fantastic people and technologies there, even though it was hard work at times. I saw Fraunhofer as an investor, and I still say “we” when I talk about Fraunhofer, which is a good sign. I have a lot of affection for the organization, and I’m still carrying out projects with Fraunhofer today. Of course, we also had our moments. I still find I have a lot to learn from it, for example by analyzing the decisions I made at the time. I also balance them against my decisions in my private life and in my startup. That’s why I recently posted on LinkedIn: Everything is fractal.


 Like in the Mandelbrot set?


There’s a structure, and when you zoom in, it’s the same structure again. It was at a lecture by Benoit Mandelbrot in Munich in the early 1990s that I got the idea for a theory. I haven’t expressed it in scientific terms yet, but I realized that there are certain things that we can keep on finding and using again and again in different areas of life.


There are mechanisms in technology that we are also confronted with on a personal or a social level. We can carry them over from one line of work to another, allowing us to approach problems in a structured way. That’s how I successfully manage so many diverse projects that other people see as completely unrelated. On the other hand, structure doesn’t mean only being able to do certain things. There always needs to be flexibility. It took me a long time to realize that was a skill, or even a strength.


I often used to feel like my fellow human beings didn’t understand me. That feeling got especially bad in 2007, which is why Markus Riester — who went on to found Multiphoton Optics with me in 2013 — recommended the book “Wild Duck” by Gunter Dueck to me. That book gave me an insight into how I tick and what “category” of person I am, allowing me to train myself to interact better with people who have a different way of thinking from me. Unfortunately, that’s most people, but it’s no use talking at cross-purposes all the time. Whenever I forget that my thoughts follow a different set of “steps” from most other people, I pick up “Wild Duck.”



As well as your consultancy work, you’re also developing the Society6.0 project. What do you want to achieve with it?


Society6.0 - Bewegung für Menschen und Umwelt is a registered cooperative association currently in the process of being established. The documents should be with the registration court in the meantime. We want a movement for people and the environment. We are a network for a sustainable and responsible society addressing all topics in the areas of economy, technology and social issues, because our societal development and the urgent topics at hand can no longer be viewed in isolation. By taking a holistic approach to empower people at every level, we are working on the transformation from an industry-based society to a knowledge-based society.. We aim to empower everybody to develop their own strengths and use them for themselves and others. Many people get stuck in a job or situation because they’re afraid of change. That’s what our cooperative association Society6.0 aims to fix. Don’t complain about it, do it!


We want to bring associations, institutes, businesses, students, unemployed people and everyone else together in one network — it’s the only way to change our society for the better. We need properly presented facts that are not guided by an election campaign or by interest groups, so we can prevent society from being divided further. We’ve even gained our first member from the United States. Our ambition is to start a global movement and prove that we in Germany can produce innovative ideas and create socio-economic disruption. We need a strong Europe, and Germany has an important part to play in achieving that — not by distributing money but by making sure everybody is empowered. We need productive industries, trades and infrastructure services.



How are you going to achieve those goals?


We are offering events and seminars, for example in our launch events “What can technologies do for sustainability?” or “Sustainability in construction” or even “Green data centers.” Our events are being held in German and English, and I’ve already managed to book some outstanding speakers. The only concern is that, so far, all the speakers are men. Another example is a series of seminars for children on watchmaking, which we are offering in several locations in Germany in partnership with Rolf Lang Dresden. We want to get involved at an early stage of development, so we’re particularly encouraging children and teenagers, because children and teenagers are just cool. They’re fearless. Imagine if adults had to learn to walk like babies do. They’d probably be too scared of falling down to start learning at all. We need to start with children because they’re not scared of failure. They try, they do, they fail and then they keep trying. Children only develop a fear of failure when their school and environment start cutting them down to size. That’s something Germany is particularly bad at. My own experience as a mother has made me particularly aware of this: When I came back from the United States, my son was five years old, already spoke English and German, knew the alphabet and could count up to 20. In kindergarten in Germany he just got bored, and I was told that’s not good to demand such knowledge from a child.  


Do you think Germany is lacking when it comes to education?


We do too much pre-sorting and weeding out. People and children need the chance to develop. We think we have a great education system in Germany, but around 8 million of the people who go through it come out functionally illiterate — and that’s just the official figure. Half of those people are German-born. Those are the Federal Statistical Office’s figures from September 2019, and I’ve compared the figures from last year to those. How can that be a “good education system?”


On the other hand, our university system these days is excessively formal. It’s grim. Looking at my academic record, I see that I could have completed my degree, including dissertation, in seven semesters. It actually took me 13.5 semesters. That’s because I liked to ride my motorbike to France in the summer to swim and party. Did that do me any harm? Did it make me any less smart? No! So many of my friends and acquaintances did the same, and today they’re in amazing positions, managing businesses and being true to themselves. That’s why we’re not afraid of a challenge: because we had to work for everything and learn certain skills for ourselves. In today’s university and school system, we’d all have been weeded out. It’s the reason why businesses today have to spend so much time and money showing new employees how to organize or order something or approach an issue in a solution-oriented way. The problem is just being outsourced to businesses. Big corporations won’t notice if people start out being of no use to the company, because they have enough staff members and money to cushion the blow. For small businesses, though, the effects are dramatic. As a founder of a startup, I know all about that. A country with a good education system should be able to do better — that’s what we want and what we need. The activities we do through our cooperative network therefore support businesses, too.  


What’s next?


Fraunhofer has enabled me to do a lot. Without that stage of my life, I wouldn’t be where I am today. I’m optimistic and expect to spend the next few years on the Society6.0 project, as well as lots of other cool technological things. I’m not short of ideas. Of course, there are always optimizations to be made. Without the people who have been there with me, starting with my family, my colleagues at university, in the US and, of course, especially at Fraunhofer, I wouldn’t have achieved my goals. That’s not empty praise, either — I really enjoyed working at Fraunhofer, even those times when the system drove me crazy. If you can take yourself out of what’s making you angry and instead focus on driving things forward, you can make that work, too. It’s always good to look forward.  


Thank you for sharing your ideas with us, Dr. Houbertz — we wish you every success with your latest projects!