Sabine Essig

Fabrication and characterization of silicon woodpile photonic crystals with a complete bandgap at telecom wavelengths

By using direct laser writing into a novel commercially available photoresist and a silicon-double-inversion procedure followed by tempering of the silicon structures, we realize high-quality centered-tetragonal woodpile photonic crystals with complete photonic bandgaps near 1.55 microm wavelength. The 6.9% gap-to-midgap ratio bandgap is evidenced by the comparison of measured transmittance and reflectance spectra with band-structure and scattering-matrix calculations.

Waveguides in three-dimensional photonic-bandgap materials by direct laser writing and silicon double inversion

Three-dimensional complete photonic-bandgap materials offer unique opportunities regarding the integration of optical waveguide architectures in three dimensions. However, corresponding experimental realizations are truly sparse. Here, we fabricate such waveguides using direct laser writing and a silicon double-inversion procedure. The optical characterization is in good agreement with theoretical calculations, raising hopes that even more complex architectures may soon come into reach.

Generation of adaptive coordinates and their use in the Fourier Modal Method

We present an improvement of the standard Fourier Modal Method (FMM) for the analysis of lamellar gratings that is based on the use of automatically generated adaptive coordinates for arbitrarily shaped material profiles in the lateral plane of periodicity. This allows for an accurate resolution of small geometric features and/or large material contrasts within the unit. For dielectric gratings, we obtain considerable convergence accelerations. Similarly, for metallic gratings, our approach allows efficient and accurate computations of transmittance and reflectance coefficients into various Bragg orders, the spectral positions of Rayleigh anomalies, and field enhancement values within the grating structures.

Electrochemical Modulation of Photonic Metamaterials

[∗] L.-H. Shao ,[+] M. Ruther ,[+] Prof. S. Linden ,[+] Prof. J. Weissmuller , Prof. M. Wegener Institut fur Nanotechnologie Karlsruhe Institute of Technology (KIT) Postfach 3640, D-76021 Karlsruhe (Germany) E-mail: matthias.ruther@kit.edu L.-H. Shao , M. Ruther , Prof. S. Linden , S. Essig , Prof. K. Busch , Prof. J. Weissmuller , Prof. M. Wegener DFG-Center for Functional Nanostructures (CFN) Karlsruhe Institute of Technology (KIT) D-76131 Karlsruhe (Germany) M. Ruther , Prof. S. Linden , Prof. M. Wegener Institut fur Angewandte Physik Karlsruhe Institute of Technology (KIT) Wolfgang-Gaede-Strasse 1, D-76128 Karlsruhe (Germany) S. Essig , Prof. K. Busch Institut fur Theoretische Festkorperphysik Karlsruhe Institute of Technology (KIT) Wolfgang-Gaede-Strasse 1, D-76128 Karlsruhe (Germany) Prof. S. Linden Current Address: Physikalisches Institut, Universitat Bonn, Nusallee 12, D-53113 Bonn (Germany) [+] These authors have contributed equally to this work

Polarization anisotropy and cross-polarized transmission in thin film opal-based photonic crystals

Polarization anisotropy of the zero order forward-diffracted and the off-resonance transmitted light in the 3-dimensional thin film opal photonic crystals has been numerically computed and experimentally measured. Studies of the polarization anisotropy as a function of the incidence and azimuth angles of the incoming light have revealed strong anisotropy changes at diffraction resonances and in the ranges of the multiple-band diffraction. The opposite sign of the polarization anisotropy for different diffraction resonances has been observed. The cross-polarization coupling has been measured and identified as one of the reasons for changing the anisotropy sign. The correlation of the lattice ordering and the magnitude of the light polarization anisotropy has been demonstrated.

Polarisation anisotropy in colloidal photonic crystals

In-depth investigation of the polarisation anisotropy of the reflected and transmitted light in 3-dimensional photonic crystals has been undertaken using the numerical experiment with perfectly ordered colloidal crystal in comparison to measurements of two types of such crystals with intrinsic disorder. Merging of the critical angle of diffraction to the Brewster angle of a crystal as an effective medium has been shown. Equalising of anisotropy magnitudes of different resonances across the range of avoided crossing of their dispersion branches has been observed. The different appearance of the polarisation anisotropy in resonances in transmission and reflectance has been demonstrated. The usually opposite character of the resonance anisotropy with respect to the off-resonance anisotropy has been presented.

Photonic metamaterials by direct laser writing

We present a planar magnetic metamaterial fabricated using 3D direct laser writing and silver chemical vapor deposition as well as a negative-index bi-anisotropic metamaterial metallized via silver shadow evaporation. Calculations and experiments show good agreement.