Robust polarization twist by pairs of multilayers with tilted optical axes

Abstract

Polarization of photonic beams makes a continuous information carrier and thus modifying it dramatically within a short distance is desirable for numerous optical devices. The easiest way to emulate anisotropy, which is a prerequisite for any polarization conversion, is utilizing thin slices of plasmonic multilayers, whose performance is limited by the inevitable losses. Such a difficulty gets overcome by using pairs of these slices in a bilayer configuration and optimizing the direction of their optical axes. In this sense, the losses are balanced by the interplay between fields in each slice and the overall interference scheme yields closer-to-desired transmissions. Several realistic designs giving effective polarization twists of substantial immunity to fabrication defects or misalignment in oscillation frequency and incidence angle, are obtained. These structures are both efficient and minimalistic; thus can be useful in many photonic systems requiring robust polarization engineering and compact packaging.