  A multi-element interdigitated photoconductive emitter for broadband THz
polarization rotation is proposed and experimentally verified. The device
consists of separate pixels for the emission of horizontally and vertically
polarized THz radiation. The broadband (0.3-5.0THz) nature of the device is
demonstrated, and the polarization angle of the generated far-field THz
radiation is shown to be readily controlled by varying the relative bias
voltage applied to the horizontally and vertically emitting pixels. The device
is scalable in design, and with its simple method of polarization rotation it
allows the modulation of the generated THz polarization at rates significantly
faster than those achievable in ellipsometry systems based on mechanically
rotating components.
