Quasi-optical Josephson-junction oscillator arrays

Abstract

Josephson junctions are natural voltage-controlled oscillators capable of generating submillimeter-wavelength radiation, but a single junction usually can produce only 100 nW of power and often has a broad spectral linewidth. We are investigating two-dimensional quasi-optical power combining arrays of 10^3 and 10^4 NbN/MgO/NbN and Nb/Al-AlO/Nb junction to overcome these limitations. The junctions are DC biased in parallel and are distributed along interdigitated lines. The arrays couple to a resonant mode of a Fabry-Perot cavity to achieve mutual phase-locking. Devices have been produced, and the I-V characteristics of these arrays have been measured, but not as of now in the Fabry-Perot cavity. In this paper, the important features of the design and the critical device properties are discussed.