<title>Highly polarization selective diffractive optical elements for use in optical interconnection and routing systems</title>

Abstract

Diffractive optical elements (DOEs) have proven to be useful components in optical interconnection and routing systems, especially where volume, weight, and design flexibility are important. We show that it is possible to increase the functionality of DOEs by making them polarization-selective, i.e. anisotropic. Several anisotropic diffractive optical elements (ADOEs) were fabricated in calcite by means of simple wet etching technology, and characterized experimentally. Both anisotropic Fresnel lenses and gratings have been studied. First order efficiencies of more than 12% and contrast ratios of over 110:1 have been observed for off-axis elements. To demonstrate the potential of these ADOEs we have built an electrically controlled beam deflector which consists of a liquid crystal polarization modulator and an anisotropic grating. An incident beam can then be deflected to two different pairs of points by changing the voltage applied to the liquid crystal modulator. We show the high contrast ratios observed when simultaneously measuring the intensity in each point while the voltage on the liquid crystal is modulated.