Subwavelength Quarter-Waveplate Composed of L-Shaped Metal Nanoparticles

We propose a subwavelength quarter-waveplate composed of four L-shaped nanoparticles that act as optical nanoantennas and investigate its optical properties using the finite-difference time-domain method. When polarization of the incident beam is parallel to one arm of the antenna, polarization of the scattering light rotates 45A degrees with respect to that of the incident beam due to the symmetry of the L-shaped nanoantennas. Phase retardation is generated by changing the arm length of the antennas. The influence of the distance between the L-shaped nanoantennas on the far-field radiation is also discussed.