1. Fraunhofer Heinrich Hertz Institute HHI Fiber Optical Sensor Systems Am Stollen 19 H 38640 Goslar Germany
2. Clausthal University of Technology Institute of Energy Research and Physical Technologies Am Stollen 19 B 38640 Goslar Germany
3. Clausthal University of Technology Institute of Organic Chemistry Leibnizstr. 6 38678 Clausthal-Zellerfeld Germany