1. Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden
2. Photonics Laboratory, Department of Microtechnology and Nanoscience (MC2), Chalmers University of Technology, Gothenburg, Sweden
3. OpenLight Photonics, Mountain View, CA, USA
4. Department of Photonic Engineering, Technical University of Denmark, Lyngby, Denmark
5. Department of Applied Mathematics and Computer Science, Technical University of Denmark, Lyngby, Denmark