1. Abbe Center of Photonics, Friedrich Schiller University Jena, 07743 Jena, Germany.
2. Optical Quantum Technology Department, Fraunhofer IOF, 07745 Jena, Germany.
3. CREOL, College of Optics and Photonics, University of Central Florida, Orlando, FL 32816, USA.
4. Faculty of Physics, Warsaw University of Technology, 00-662 Warsaw, Poland.
5. Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089, USA.