Universität Stuttgart

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Subject: search.filters.subject.530Institute: search.filters.UBSInstitut.Stuttgart Research Centre of Photonic Engineering (SCoPE)Institute: search.filters.UBSInstitut.4. Physikalisches InstitutEnd date: 2019Author: search.filters.author.Schäferling, Martin

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Now showing 1 - 4 of 4
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    Tailoring enhanced optical chirality : design principles for chiral plasmonic nanostructures
    (2012) Schäferling, Martin; Dregely, Daniel; Hentschel, Mario; Giessen, Harald
    Electromagnetic fields with strong optical chirality can be formed in the near-field of chiral plasmonic nanostructures. We calculate and visualize the degree of chirality to identify regions with relatively high values. This leads to design principles for a simple utilization of chiral fields. We investigate planar geometries which offer a convenient way to access the designated fields as well as three-dimensional nanostructures which show a very high local optical chirality.
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    Modeling of second-harmonic generation in periodic nanostructures by the Fourier modal method with matched coordinates
    (2018) Defrance, Josselin; Schäferling, Martin; Weiss, Thomas
    We present an advanced formulation of the Fourier modal method for analyzing the second-harmonic generation in multilayers of periodic arrays of nanostructures. In our method, we solve Maxwell’s equations in a curvilinear coordinate system, in which the interfaces are defined by surfaces of constant coordinates. Thus, we can apply the correct Fourier factorization rules as well as adaptive spatial resolution to nanostructures with complex cross sections. We extend here the factorization rules to the second-harmonic susceptibility tensor expressed in the curvilinear coordinates. The combination of adaptive curvilinear coordinates and factorization rules allows for efficient calculation of the second-harmonic intensity, as demonstrated for one- and two-dimensional periodic nanostructures.
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    Polarization scramblers with plasmonic meander-type metamaterials
    (2012) Schau, Philipp; Fu, Liwei; Frenner, Karsten; Schäferling, Martin; Schweizer, Heinz; Giessen, Harald; Gaspar Venancio, Luis Miguel; Osten, Wolfgang
    Due to plasmonic excitations, metallic meander structures exhibit an extraordinarily high transmission within a well-defined pass band. Within this frequency range, they behave like almost ideal linear polarizers, can induce large phase retardation between s- and p-polarized light and show a high polarization conversion efficiency. Due to these properties, meander structures can interact very effectively with polarized light. In this report, we suggest a novel polarization scrambler design using spatially distributed metallic meander structures with random angular orientations. The whole device has an optical response averaged over all pixel orientations within the incident beam diameter. We characterize the depolarizing properties of the suggested polarization scrambler with the Mueller matrix and investigate both single layer and stacked meander structures at different frequencies. The presented polarization scrambler can be flexibly designed to work at any wavelength in the visible range with a bandwidth of up to 100 THz. With our preliminary design, we achieve depolarization rates larger than 50% for arbitrarily polarized monochromatic and narrow-band light. Circularly polarized light could be depolarized by up to 95% at 600 THz.
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    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.