Singular Optics Research in the Laser Teaching Center

In the last few years there has been a great deal of interest in the optics community and at the Laser Teaching Center (LTC) in singular optics, the study of wave phenomena that involve mathematical singularities. Examples from nature include rainbows (in which light is concentrated at a particular scattering angle by raindrops), the polarization of the clear blue sky, and optical vortices (OV's). Optical vortices resemble tornadoes in their circular motion (of the optical phase) about a dark center (a region where phase is undefined and light intensity vanishes). Optical singularites have both considerable intrinsic interest and also numerous possible applications in astronomy, quantum computing and medicine. The LTC projects have involved about ten high school, undergraduate and graduate students so far, who usually worked independently of each other but who each built on the previous work and experience. They are described in the Student Projects portion of the LTC web site at http://laser.physics.sunysb.edu/.

The initial LTC experiments in 2001-2002 were related to certain laser beams, called Laguerre-Gauss (LG) modes, that contain OV's. SeungHyun Lee and Alex Ellis created LG modes by manipulating the phase of Hermite-Gauss laser beams obtained from an open-cavity laser or by other means. Patrick Neuernberber added an interferometer to display the beautiful spiral phase patterns of the OV modes. In 2004 Azure Hansen studied OV's created with a computer-generated diffraction grating (CGH) containing a "fork" discontinuity, and explored the rapidly growing literature of the field. That summer Anirudh Ramesh and Yaagnik Kosuri investigated the feasibility of using CGH-created vortices in an "optical spanner" that could rotate as well as translate micron-sized particles. In 2005 Greg Caravelli, Amol Jain and Ulrike Endesfelder studied ways to efficiently create OV's using phase plates made from nothing more than pieces of cracked, cut or bent plastic. Our current research is related in part to devices called spatial light modulators which can create arbitrary OV's under computer control. Simplified means to produce various forms of polarized light useful for this research have also been studied, as described in a separate abstract.

We are indebted to many individuals for their support and assistance, including: Kiko Galvez (Colgate University), Grover Swartzlander (University of Arizona, Tucson), Miles Padgett (Glasgow University) and Sir Michael Berry (Bristol University). This research was supported by NSF-REU grants and the Simons Fellowship program.