Measurements of non-linear sub-THz quasi-optical devices

The paper presents recent developments in designing quasi-optical multipliers in the sub-THz frequency domain. An extensive measurement campaign is described in detail in which issues are addressed concerning the non-trivial nature of the problems met. In particular, attention is paid to impedance measurements of the core element, the integrated antenna-multiplier (dubbed the `multenna'), together with the associated experimental apparatus for detection of its higher-order harmonics. Finally, use of a light-sensitive semiconducting organic polymer is demonstrated as a tuneable dielectric that will enable elements of a multenna array to be phase-locked for generation of coherent emission.