May 11 2010
It has been known for many years that careful control of the polarization of light can impact optics and photonics technologies. For example, tiny nanostructures are known to be able to capture light from a region much larger than their size if the polarization of the laser illumination is designed correctly. Dark spots in a beam known as optical vortices can produce new and intriguing effects when used along with polarization control in a microscope.
To highlight breakthroughs in this area, the editors of Optics Express, the Optical Society's (OSA) open-access journal, today published a special focus issue on Unconventional Polarization States of Light. The issue was organized and edited by Thomas G. Brown of the Institute of Optics at the University of Rochester and Qiwen Zhan of the University of Dayton.
"What once was a side curiosity of optics is now joining the mainstream, both in fundamental investigations and in applications," said Brown. "Research in this focus issue will cover polarization breakthroughs that have the potential to affect a broad range of disciplines – from nanomaterials to laser devices."
Summary
The polarization of light can play an important role in optical trapping, interaction with nanostructures, and focusing in microscopy. The seminal work in the mid-1990s by Colin Sheppard, now at the National University of Singapore, and Dennis G. Hall now at Vanderbilt University launched a flurry of studies in the last decade on the creation and focusing of polarized beams that have certain geometrical symmetries. Beams with a spoke-like 'radial' polarization were of particular interest because of their potential for creating small focal regions of axially polarized light, a key requirement for interacting with nanostructures and coupling to fields tightly confined to metal surfaces. For unconventional polarization states of light, the geometrical arrangement of the polarization can produce vortex behavior in beam propagation, a result that has intrigued physicists and changed how optical engineers think about illumination in microscopes and lithography systems. Meanwhile, the creation of unconventional polarization states within compact laser cavities has offered new ways to begin incorporating these states into more complex optical systems.