Laser Beams with Phase Singularity

Department of Information and Communication Engineering, The University of Electro-Communications, Japan

2.30pm, Wednesday 2 May 2001, Virtual Reality Theatre (AS406), Applied Sciences Building

A phase singularity is a structure in a complex field such that integration of the phase gradient along a closed path around it yields 2mp, where m is an integer and called the charge of the phase singularity. Using an electron-beam lithography technique, we have fabricated transmission and reflection holograms that generate phase singularities when illuminated with a laser beam. The resulting phase distribution was examined in detail, and it was found that in all of the cases phase singularities with m > 1 had split into m individual charge-1 singularities. The phenomenon was analyzed through numerical simulation and experiment to show that astigmatic aberration can play an important role.

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