  We present an electrically tunable terahertz two dimensional plasmonic
interferometer with an integrated detection element that down converts the
terahertz fields to a DC signal. The integrated detector utilizes a resonant
plasmonic homodyne mixing mechanism that measures the component of the plasma
waves in-phase with an excitation field functioning as the local oscillator.
Plasmonic interferometers with two independently tuned paths are studied. These
devices demonstrate a means for developing a spectrometer-on-a-chip where the
tuning of electrical length plays a role analogous to that of physical path
length in macroscopic Fourier transform interferometers.
