Tunable polarization response of a planar asymmetric-spiral infrared antenna

We present measurements at 10.6 mu m that demonstrate electronic tuning of the polarization response of asymmetric-spiral infrared antennas connected to Ni-NiO-Ni diodes. Continuous variation of the bias voltage applied to the diode results in a rotation of the principal axis of the polarization ellipse of the spiral antenna. A 90 degrees tuning range is measured for a bias voltage that varies from - 160 to + 160 mV. This effect is caused by a small asymmetry of the deposited diode contact or by a variation of the detector capacitance with the applied bias voltage. (C) 1998 Optical Society of America.