Non-Hermitian photonics: New functionality by symmetry, new opportunity beyond symmetry
Liang Feng, University of Pennsylvania
A stream of photons is typically topologically trivial, nevertheless, its full-vector nature intrinsically endows light with full capability of creating and carrying unique symmetry and topology, especially non-Hermitian symmetries that cannot be easily implemented in condensed matter. Explorations of symmetry and topology on a photonic platform not only deepen our understanding of fundamental physics, but also enable novel material properties to facilitate technological breakthroughs for photonic applications. In this seminar, I will present our recent efforts on investigating symmetry and topological physics for the next generation of optical communication and information technology. We demonstrated an orbital angular momentum (OAM) microlaser that structures and twists the lasing radiation at the microscale, which can provide an additional OAM-based information dimension to meet the growing demand for information capacity. By strategically interfacing non-Hermitian photonic materials and topological physics, we realized the dynamic control of robust topological transmission links of light inside the bulk of a photonic topological insulator, routing optical signals in a highly flexible and scalable manner. Furthermore, we conducted a supersymmetry-based formalism to achieve higher-dimensional microlaser phased arrays producing high-radiance, small-divergence laser beams with orders of magnitude enhancement in energy density. Additionally, beyond the known quantum symmetry paradigms we are exploring new types of light-matter interaction solely governed by non-Hermiticity of the system, arising from the first-principle electromagnetic design. For example, our recently discovered photonic active resonances have no counterpart in condensed matter and previously studied passive photonic systems.