Interview with Alexander Fürbach

When Prof. Krausz and his Vienna-team produced the first attosecond flashes of light in 2001, Alexander Fürbach was a doctoral student in the group led by Ferenc Krausz at the University of Vienna. At that time he was involved in the development of femtosecond lasers. After working at "Femtolasers", he planned to go to Australia for two years. It has now been almost 20 years. He is now a professor at the Department of Physics and Astronomy at Macquarie University in Sydney. Here he tells about his passion for femtosecond lasers and what it's like to live and work in Australia.

As a young doctoral student in the LAP team, you dealt with the development of femtolasers in Vienna. What was the goal of the work at that time?

At the time I did my PhD, the use of femtosecond lasers was very much limited to scientific applications in a controlled laboratory environment. The main aim of my work was the development of novel ultrafast laser sources for micromaching applications, with the ultimate goal of realizing laser systems that could also be used in industry or medicine, for example as a replacement for the dreaded mechanical dental drill. One particular approach that our team pioneered back then was the concept of a chirped-pulse oscillator (CPO) for the generation of high-power femtosecond pulses without external amplification. This new technology was eventually translated into a commercial product by Femtolasers GmbH and enabled us for example to demonstrate the possibility of selectively analyse individual oil-inclusions in quartz crystals for petrochemical applications. To come full circle, one of these laser systems is now the workhorse of many of my research projects here at Macquarie University in Sydney.


You were also there when the team produced the first attosecond flashes of light. How did you experience this event?

I not only remember the event itself, but also the long and difficult road to get there. While I was not directly involved in this work, it was on multiple occasions that I would come to the lab early morning to greet some very tired colleagues of mine after yet another round of all-night measurements. We knew that other groups were also working on the generation of attosecond pulses and the pressure was enormous. For me the main reasons that our group eventually succeeded were the comprehensive scientific expertise that existed within the team and maybe even more so, Ferenc’s very unique leadership skills. He always managed to motivate all his students and coworkers and create a fantastic team-spirit that made us all feel proud of being part of something very special. And when eventually the first “atto-flash” was then finally confirmed, everyone was ecstatic that all the hard work eventually paid off. It was a great time.


Today you are still dealing with femtosecond laser technology. What is the focus of your research team today?

The main focus of my research activities is the use of ultrafast lasers for the inscription of photonic structures into transparent dielectric materials. When an ultrashort laser pulse is tightly focused into a transparent material, a highly localized change in the refractive index can be induced and this provides the basis for the so-called femtosecond laser direct-write technique. While the same principle can be used in application fields as diverse as astro-photonics or quantum-information, my team and I are currently focusing on the development of hybrid waveguide-fibre sources for the mid-infrared spectral region, in particular ultrafast and ultrabroadband laser systems. This specific part of the electromagnetic spectrum has long attracted much scientific and technological interest due to the fact that virtually all molecules have their rotational-vibrational absorption lines in this range. For this reason, the mid-infrared is often referred to as the “molecular fingerprint” region. Owing to the high-impact applications that result from the strong molecule-photon interaction, such as trace molecular detection for airport security screening and non-invasive breath analysis, mid-IR photonics has become a hot topic in modern optics research.


Why did you end up in Australia?

After having spent the first 30 years of my life in Vienna, and after having fallen in love with Australia during a long camping holiday, I decided that I would like to take the opportunity to work as a Post-Doc at the University of Sydney for two years, to use this time to experience the city and the country, and then to move back to Austria. Then came an early-career fellowship and a tenure-track position at Macquarie University and now, almost 20 years later, I am still in Sydney. In the meantime, I became dual Austrian-Australian citizen and I find it still hard to believe that my daughter is already in year 3 at school and that my little boy is about to start school next year. Looks like Sydney is going to be my home for a much longer time than originally expected.


You are a professor at Macquarie University in Sydney. What is life and work like in Sydney?

When I came to Australia in 2004 I was amazed by how laid-back the country was compared to Vienna. While “no worries” is still a phrase that can be heard very often, life in Sydney has also become more and more fast-paced over the years. Houses and childcare are ridiculously expensive, traffic is bad (unless there is a pandemic) and having a mortgage the size of a small country (something I would have never even considered when I was still living in Europe) has become something that is just normal. Academic live is highly competitive as everywhere in the world with the usual and constant pressure to publish and to attract funding. Still, a short drive to a stunning beach on a sunny 20°C winter day reminds me that Sydney is a beautiful city. The suburb that I live in, called Wollstonecraft, features some amazing parkland with breathtaking views of the city skyline with its famous opera house, even on a hot summer’s day there is always a nice ocean breeze and the Blue mountains, a paradise for rock-climbing and hiking (called “bushwalking here in Australia) are only an hour’s drive away. I guess overall, I can’t complain about life and work in Sydney.


If you imagine laser technology in 20 years. What does it look like?

Laser technology is already ubiquitous, and I think that this trend will continue in the next 20 years. With respect to my own research activities into mid-infrared laser systems my hope is that in 2040 we will have access to compact and field-deployable spectroscopy systems that are capable of analyzing the molecular composition of gases, liquids and solids with unprecedented selectivity and sensitivity. This will enable for example the early detection of various forms of cancer just from the exhaled breath of a person or the precise measurement of the concentration of various trace-gases that are present in the atmospheres for constant air-quality monitoring. My prediction is that in 20 years, these systems will be so small that they can be integrated into miniature drones so that they can be employed even in remote and unsafe locations. Only time will tell if I am right but my group and I are doing our best to make this vision a reality one day.