The exploitation of the resonant effects of sub-wavelength structures enables us to enter the nano-optical regime. Structuring diffractive optical elements (DOE) with subwavelength structures means adding an additional degree of freedom in the design of compact optical elements.
We use the Soft-UV-Nanoimprint-Lithography (NIL) as a potentially cost-effective manufacturing method to reproduce small structures on a large scale. Using both the effective medium approximation (EMA) and rigorous methods (RCWA), we designed and manufactured a binary subwavelength-structured form-birefringent diffraction grating, which acts as a polarizing beamsplitter for a wide range of incidence angles −30°… +30°.
The designing and manufacturing methods we refined and developed, potentially enable us to realize integrated compact optical measurement systems, such as common-path interferometers. Furthermore, our methods can be applied to realize other polarization-dependent DOEs and can be extended for multilevel elements.