Generation of High Efficiency Longitudinally Polarized Beam using High NA Lens Axicon and Dedicated Phase Filter

We propose to use pure phase filter in combination with high NA lens axicon to achieve high efficient longitudinally polarized beam with a subwavelength spot size and large depth of focus using hyper geometric Gaussian beam. Using this system, the spot size is reduced to 0.392 λ and the depth of focus is increased to 7 λ. The efficiency of such system is found to be 87%. This high efficient longitudinally polarized beam generated by hyper geometric Gaussian beam is useful for most of the near-field optics applications.