Polarization-multiplexed multifocal arrays by a π-phase-step-modulated azimuthally polarized beam.

We demonstrate a polarization-multiplexed multifocal array capable of individually manipulating the focal polarization state in each focal spot. Breaking the rotational phase symmetry through adding a π-phase-step to an azimuthally polarized beam leads to a linear focal polarization state with high polarization purity. Through the superposition of such modulated azimuthal polarization fields at the back aperture of the objective, multifocal arrays with individually controllable and non-identical polarization states can be achieved. In addition, this approach exhibits a sub-diffraction-limited feature with an improved lateral resolution of 10% reduced full width at half-maximums in each linearly polarized focal spot. Consequently, applying this technique to parallel polarization-multiplexed optical recording is demonstrated.