1. Lund Laser Centre; Department of Physics; Lund University; Sölvegatan 14 SE-221 00 Lund Sweden
2. Center of Optical and Electromagnetic Research; South China Normal University; Guangzhou 510006 China
3. Centre for Animal Movement Research; Department of Biology; Lund University; Sölvegatan 37 SE-223 62 Lund Sweden