Segmented subwavelength silicon gratings manufactured by high productivity microelectronic technologies for linear to radial/azimuthal polarization conversion

Abstract

A polarization rotation is realized by subwavelength binary gratings, where the round trip phases of the smallest grating modes are fixed to the smallest possible integer numbers of 2π allowing a phase difference of π between TE and TM polarizations and almost 100% transmission. The principle is applied to a polarization transformation in the 1030 to 1064-nm wavelength range, using a segmented polarization rotating element converting a linearly polarized incidence to a radial or azimuthal polarization distribution. The elevated costs of such kinds of polarization transformers based on assembled birefringent crystals are avoided by using mass-fabrication compatible silicon-on-insulator technology on a wafer scale. It shows the general potential of microelectronic technology, concerning the batch manufacturing of wavelength-scale diffractive, grating-based elements for processing free space waves.