Miniature circular polarization analyzer with spiral plasmonic lens.

A simple spiral plasmonic lens is studied both analytically and numerically. Owing to the geometric phase effect, a spiral plasmonic lens focuses the left-hand and right-hand circular polarizations into spatially separated plasmonic fields. Such a spatial multiplexing of the field distribution is utilized in miniature circular polarization analyzer design. A circular polarization extinction ratio better than 100 is obtainable with a device size as small as 4lambda(spp). The spiral plasmonic lens provides efficient plasmonic focusing while it eliminates the requirement of centering the incident beam to the plasmonic lens, making it suitable for full Stokes parameter polarimetric imaging applications.