Open confocal resonators with quasi-optical arrays to measure THz dynamics of quantum tunneling devices

摘要

Abstract: A semi-confocal etalon has been sued as a quasi-optical cavity to explore the dynamical conductance of Bloch- oscillating superlattices at terahertz frequencies. To maintain both DC and irradiated field uniformity and to maximize the coverage of the cavity mode with the devices of interest, the tunneling structures have been photolithographically fabricated into micro-sized mesa- isolated devices forming a quasi-optical square array interconnected by a metal grid with a period which is less than the wavelength in the semiconductor of the IR probe radiation. At a given bias on the device array and scanning the cavity through a resonance, the loss and reactance of the tunneling devices embedded in the array is measured by detecting a change in the position and line shape of the cavity resonance. Transmission measurements of the cavity loading by the biased quasi-optical arrays at frequencies from 250GHz to 3.0THz will be presented and compared to theoretical predictions. !1