1. Institute of Photonics, Vienna University of Technology, Gußhausstraße 27-29, 1040 Vienna, Austria
2. AMO GmbH, Otto-Blumenthal-Straße 25, 52074 Aachen, Germany
3. Institute of Solid State Electronics, Vienna University of Technology, Floragasse 7, 1040 Vienna, Austria
4. National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044, Japan