1. Nonlinear Photonics Group; Institute of Applied Physics, University of Münster; Corrensstrasse 2/4 48149 Münster Germany
2. Physics and Astronomy Department; University of Padova; via Marzolo 8 35131 Padova Italy
3. Nonlinear Optical Lithography Group; Institute of Applied Physics, University of Münster; Corrensstrasse 2/4 48149 Münster Germany