@article{65316,
  abstract     = {{Metasurfaces are powerful tools for manipulating light using small structures on the nanoscale. In most metasurfaces, near-field couplings are treated as being unfavorable perturbations. Here, we experimentally investigate a structure consisting of sinusoidally modulated silicon waveguides where near-field coupling of local resonances leads to negative coupling, i.e., a negative coupling constant. This gives rise to wave-vector-dependent eigenstates of elliptical, linear, and circular polarizations. In particular, fully circular polarization states are not only present at a single point in momentum space (k-space) but also along a line. This circular polarization line, as well as a linear polarization line, emanates from a polarization degeneracy at the Dirac point. We experimentally validate the existence of these eigenstates and demonstrate the energy-, polarization-, and wave vector dependence of this metasurface as well as its sensitivity to fabrication tolerances. By tuning the incident k-vector, certain polarization-energy eigenstates are strongly reflected, allowing for uses in angle-tunable polarization filters and light sources.}},
  author       = {{Wetter, Helene and Wingenbach, Jan and Rehberg, Falk and Gao, Wenlong and Schumacher, Stefan and Zentgraf, Thomas}},
  issn         = {{2330-4022}},
  journal      = {{ACS Photonics}},
  keywords     = {{metasurface, waveguides, Dirac point, polarization, negative coupling}},
  pages        = {{2128--2133}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Polarization- and Wave-Vector Selective Optical Metasurface with Near-Field Coupling}}},
  doi          = {{10.1021/acsphotonics.5c02865}},
  volume       = {{13}},
  year         = {{2026}},
}

@inproceedings{39027,
  abstract     = {{We experimentally investigate the generation of continuous-wave optical squeezing from a titanium-indiffused lithium niobate waveguide resonator at low and high frequencies. The device promises integration with different platform chips for more complex optical systems.}},
  author       = {{Domeneguetti, Renato R. and Conradi, Hauke and Kleinert, Moritz and Kießler, Christian and Stefszky, Michael and Herrmann, Harald and Silberhorn, Christine and Andersen, Ulrik L. and Neergaard-Nielsen, Jonas Schou and Gehring, Tobias}},
  booktitle    = {{2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference}},
  keywords     = {{Optical systems, Polymer waveguides, Quantum key distribution, Quantum light sources, Squeezed states, Waveguides}},
  pages        = {{eb_4_1}},
  publisher    = {{Optica Publishing Group}},
  title        = {{{Nonlinear waveguides for integrated quantum light source}}},
  year         = {{2021}},
}