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HL: Fachverband Halbleiterphysik

HL 26: Poster II

HL 26.36: Poster

Mittwoch, 11. März 2026, 09:30–11:30, P1

Role of a Quarter-Wave Plate in Resonant Laser Spectroscopy: Signature of Spin-Orbit Interactions of Light — •Wenze Lan, Anton Lögl, and Bernhard Urbaszek — Institute for Condensed Matter Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany

Resonant laser spectroscopy is a powerful technique for probing the intrinsic optical transitions, coherence properties, and spin dynamics of single quantum emitters. Although polarization-based dark-field confocal microscopy enables nearly background-free detection of resonant fluorescence [1], the role of an additional quarter-wave plate in further improving extinction has remained unclear. Here, we elucidate the mechanism by which a commercial quarter-wave plate enhances polarization extinction in a simple confocal geometry. Under cross-polarization conditions, the transmitted beam exhibits a robust first-order Hermite-Gaussian mode, which explains the improved background suppression and we identify it as a direct signature of spin-orbit interactions of light [2-3]. Our findings inspire applications in polarization optics, nanophotonics, and quantum photonics. [1] Rev. Sci. Instrum. 84, 073905 (2013); [2] J. Opt. 15, 014001 (2013); [3] Nat. Photon. 9, 796-808 (2015).

Keywords: Resonant laser spectroscopy; Polarization extinction; Quarter-wave plate; Spin-orbit interactions