Polarization-Maintaining Diffractive Elements for Off-Axis Terahertz Digital Holography

Abstract

Off-axis digital holography in the terahertz waves allows three-dimensional visualizations of optically opaque volumetric objects in a single exposure and with angular separation of the zero-order component. Forming the tilted reference beam usually requires a set of mirrors, which can disturb the polarization, causing the loss of contrast in fringes at the detector. Here we present a mirror-less approach with 3D-printed transmissive diffractive optical elements, providing unaltered polarization and successful holographic measurements at 0.1 THz without any pre- or postprocessing of interference fringes.