Polarizing Beam Splitter: A New Approach Based on Transformation Optics

Abstract

Standard optical elements (e.g. lenses, prisms) are mostly designed of piecewise homogeneous and isotropic dielectrics. However, in theory one has far more possibilities to influence electromagnetic waves, namely all the components of the permittivity and permeability tensors. In the past few years, on the one hand, new micro fabrication methods allowed for new freedom in controlling of the optical parameters using so called artificial metamaterials. On the other hand, the theory of transformation optics has given a somewhat intuitive approach for the design of such structures. The most popular feature of this kind is certainly optical cloaking (i.e. [1,2]). However, the full capabilities of other transformation optical devices are far from being fully explored. In my work, I focused on pure dielectric structures in a non-resonant and therefore non-lossy regime. Although the relative permittivity one can achieve this way is limited by the available natural dielectrics, a broad spectrum of features can be realized.

A polarizing beam splitter was chosen as the object of study since the use of transformation optics in this case provides some features that may be of interest for applications. Namely, the deviation angle does not vary as a function of tilts or shifts of the structure with respect to the incoming beam. Similar concepts have been proposed previously [3,4], but none of them has been realized so far. Finite element simulations of a full metamaterial structure have been carried out and a practical method for the fabrication of the device using direct laser writing [5] is proposed.