Browsing by Author "Yin, Xinghui"

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Open Access
Formation of chiral fields in a symmetric environment
(2012) Schäferling, Martin; Yin, Xinghui; Giessen, Harald
Chiral fields, i. e., electromagnetic fields with nonvanishing optical chirality, can occur next to symmetric nanostructures without geometrical chirality illuminated with linearly polarized light at normal incidence. A simple dipole model is utilized to explain this behavior theoretically. Illuminated with circularly polarized light, the chiral near-fields are still dominated by the distributions found for the linear polarization but show additional features due to the optical chirality of the incident light. Rotating the angle of linear polarization introduces more subtle changes to the distribution of optical chirality. Using our findings, we propose a novel scheme to obtain chiroptical far-field response using linearly polarized light, which could be utilized for applications such as optical enantiomer sensing.
Open Access
Functional complex plasmonics : understanding and realizing chiral and active plasmonic systems
(2016) Yin, Xinghui; Giessen, Harald (Prof. Dr.)
The present thesis concerns itself with the theoretical study and experimental realization of complex plasmonic systems for highly integrated nanophotonic devices and enhanced chiroptical spectroscopy. In particular, the two broad topics of active metasurfaces and chiral plasmonic systems are investigated to this end. In this context, the chalcogenide phase change material GeSbTe is utilized to demonstrate, for the first time, metasurface based beam steering and varifocal lensing devices. The versatility of this approach to lending active functionality to plasmonic systems is further evidenced through our realization of a chiral plasmonic system that both exhibits a wavelength tunable and handedness switchable chiroptical response. Furthermore, in order to enable a systematic study of plasmon- enhanced chiroptical spectroscopy, we rst establish and analyze canonical chiral plasmonic building blocks, in particular, the loop wire and chiral dimer structure. The results from this undertaking lead to fundamental insights for understanding complex chiral plas- monic systems. Finally, we implement chiral media in the commercial electromagnetic full- field solver Comsol Multiphysics to carry out rigorous numerical studies of the macroscopic electrodynamic processes involved in plasmon-enhanced circular dichroism spectroscopy revealing both substantial enhancement due to near-field effects as well as upper boundaries to the magnitude of such enhancements.