Author Affiliations

C. Denz,^a W. Krolikowski,⁽¹⁾ M. Saffman,⁽²⁾ and B. Luther-Davies⁽¹⁾

^(a)Institute of Applied Physics, Darmstadt University of Technology, Hochschulstr. 6, D - 64289 Darmstadt, Germany, Tel.xx-49-6151/163122, FAX: xx-49-6151/164123

⁽¹⁾Australian Photonics Cooperative Research Centre, Laser Physics Centre, Research School of Physical Sciences and Engineering, The Australian National University, Canberra ACT 0200, Australia, Tel xx-61-6/2494702, Fax xx-6-6/2490029

⁽²⁾Optics and Fluid Dynamics Department, Riso National Laboratory, Postbox 49, DJ- 4000 Roskilde, Denmark, Tel. xx-45-46 77 45 0, Fax: xx-45-46 77 45 65