Coherent Polarization Transfer through Sub-wavelength Hole Arrays

We review a series of experiments on the optical properties of metal films perforated with arrays of sub-wavelength holes. A key experiment is the transfer of polarization entanglement under plane-wave/focused illumination, where we observed a conservation/degradation of the quantum entanglement. Surface plasmons play a prominent role in the observed extra-ordinary large transmission. This is demonstrated with two supporting experiments performed with classical light, investigating: (i) the polarization and angular dependent transmission through the arrays, (ii) the generation of coherent beams of surface plasmons. Both experiments prove the directionality and TM-character expected for surface plasmon modes on a hole array.