Regensburg 2022 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 9: Focus Session: Exceptional Points and Non-Hermitian Physics in Semiconductor Systems

HL 9.1: Hauptvortrag

Montag, 5. September 2022, 15:00–15:30, H33

Exceptional points in optics: From bulk materials to one-dimensional confined systems — •Chris Sturm — Felix Bloch Institute for Solid State Physics, Universität Leipzig, Leipzig, Germany

The research of exceptional points (EP) was initiated by W. Voigt in 1902 when he discovered that for certain directions in orthorhombic crystals only one circular polarized eigenstate exists, as soon as absorption sets in [1]. These directions corresponds to EPs in the momentum space. The presence of such EP is not limited to orthorhombic crystals only and appears in many optical systems. Here we present an overview of the appearance and the properties of these EPs in bulk crystal and optically one-dimensional confined systems. We show that the properties of the EPs in bulk crystals are determined by the dielectric function and the symmetry of the crystal, which allows to distinguish between optically biaxial materials having triclinic, monoclinic or orthorhombic crystal symmetry. In the presence of an optical confinement, like in thin films or microresonators, EPs can even appear in systems consisting of optically uniaxial materials, which was recently observed experimentally (e.g. Ref. [2]). Furthermore, in contrast to bulk crystals, the properties of the EPs are determined not only by the dielectric function of the materials but depends also on the design of the system, e.g., film thickness and confinement properties.

[1] W. Voigt, Ann. Phys. 314, 367 (1902).

[2] S. Richter, Phys. Rev. Lett. 123, 227401 (2019).