  We have developed a detector of coherent terahertz (THz) radiation that can
recover the full polarisation state of a THz transient. The device is
three-contact photoconductive receiver, which is capable of recording two
time-varying electric field components of a THz pulse simultaneously. Our
receiver was fabricated on Fe+ implanted InP and showed a cross-polarised
extinction ratio greater than 100:1. The detector will be useful for
spectroscopy of birefringent and optically active materials.
