In the past decades, semiconductor lasers have found their ways into many aspects of everyday live. They are used for fiber internet or in smartphones, but are also found in less obvious areas like in self-driving cars or biological tissue analysis. A reason for their success is that these lasers are very small and efficient. However, to create more powerful but still compact lasers, simply adding a bunch of those lasers together to form a big array will not work. The device will lose an important property called coherence. Here, Sebastian Klembt and his team have addressed this issue taking inspiration from the field of mathematical topology. From the 80s on, research was done on topological transport and on topological insulators that conduct electricity on the surface and are insulating in the volume. It was the idea of 2016 Nobel laureate D. Haldane and S. Raghu in 2008 to transfer these concepts to light. Professor Klembt and his team have used topological modes to couple one small laser to the next and so on, to create a topological superlaser emitting with one specific color and with a defined phase. A design of vertical emitting lasers makes it easy to extract the light out of the device. Their approach also helps to make the superlaser robust against fabrication imperfections and outside influences due to its topological nature. Apart from scientific interest in fundamental laser physics, their breakthrough will open the door to a new generation of compact, high-power laser devices with many exciting applications.
Sebastian Klembt was born in 1983 in Kiel, Germany. Raised in Bremen with strong interest for nature, music, cycling and all things around. In Bremen I began studying physics and philosophy before I moved to Switzerland to finish my physics diploma at ETH Zürich. I obtained a PhD with highest honors from Bremen University, fabricating and studying semiconductor lasers emitting blue light. After that I joined Institut Néel in Grenoble, France for a postdoc in advances semiconductor spectroscopy, with a little bit of hiking and skiing on the side. I joined the Chair for Applied Physics in Würzburg as a Marie Skłodowska-Curie Fellow and group leader working in the field of topological photonics. In 2020 I was appointed assistant professor at the University of Würzburg within the cluster of excellence ct.qmat. Married and proud father of two.