Generation of a radially polarized light beam using space-variant subwavelength gratings at 1064 nm

The generation of radially polarized beams at a wavelength of 1064 nm by the use of a polarization transformer device consisting of space-variant subwavelength gratings (SGs) is demonstrated experimentally. The SG generates a pi phase retardation between the TE and TM polarizations, acting as a half-wave plate, reflecting the polarization vector with respect to the axes of the plate. The polarization transformer is characterized by polarization analysis and by far-field measurements. The characterization results show good agreement with theory. The device is suitable for operation with Nd:YAG lasers; thus it is attractive for biological, optical tweezers, and material processing applications. (C) 2008 Optical Society of America