Electrically driven, topological exciton-polariton laser

• Applicants: Professor Dr. Sebastian Klembt; Professor Dr. Christian Schneider
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441074308

The transfer of fundamental concepts of quantum mechanics and topology to highly integrated semiconductor optics is important for a deeper understanding of the light-matter interaction and for the development of new optical technologies. Our multidisciplinary research project is located at the boundary between solid-state physics, optics and topological physics. It places a central focus on the transfer of fundamental concepts of quantum mechanics and topology to the exciton-polariton system and more specifically to polaritonic lattice and laser systems. Exciton polaritons (polaritons) are quasiparticles resulting from the strong coupling between the electromagnetic field (cavity photon) and an excitation in a semiconductor (excitons). They are characterized, among other things, by the fact that their bosonic nature allows for a phase transition into a Bose-Einstein-type condensate. The dissipative element of these light-matter condensates leads to a radiation of monomode, coherent laser light (which enables a new class of semiconductor devices). The aim of the project is the investigation of coherent laser emission from complex lattice systems made from coupled microresonators. These lattices or chains are designed such that the resulting optical modes and their properties can be described by concepts known from topology. Topological insulators are a fascinating new class of material where topological invariants manifest by a robustness against perturbations. After initial observations of such effects in the quantum Hall effect, the concept has inspired and enriched a wide range of scientific fields. These include cold atoms, electrical circuits, and of course photonics and semiconductor optics. In this project, two of the leading junior research groups in the field of polaritronics and topological photonics will pursue the common goal of transferring topological effects to integrated polariton and semiconductor lasers. First, we will produce polaritonic lattice structures and topological polariton lasers, focusing on the particular expertise in the field of electrical operation. Furthermore, we will then investigate the laser emission of such lattice structures and topological defect modes by means of spatially and time-resolved spectroscopy methods. Our goal is to significantly expand the technology platform as part of this project, which will have a significant impact on the development of new laser and microcavity structures and thus on the wide field of integrated semiconductor optics.

• DFG Programme: Research Grants