Quarter-wave plate with subwavelength rectangular annular arrays

We propose and present a quarter-wave plate using a thin Ag film with patterned subwavelength rectangular annular arrays (RAA) on a SiO2 (glass) substrate. It is found that by manipulating asymmetric width of the annular gaps along two orthogonal directions, the transmitted amplitude and phase of the two orthogonal components can be well controlled. A quarter-wave plate at wavelength of 1.55 μm has been realized through an optimized design, in which the variation of less than 2% of the phase difference between the two orthogonal components can be obtained in an ultra-wide wavelength range of about 110 nm. It provides a great potential for applications in advanced nanophotonic devices and integrated photonic systems.