Cavity engineering of on-chip superconducting oscillators for voltage-tunable coherent mm-waves and terahertz emission with circular polarization*

  Solid-state, on-chip, integrated, and battery-operated millimetre (mm) waves and terahertz (THz) devices based on high-temperature superconducting BSCCO van der Waals can coherently and continuously radiate electromagnetic waves (EM) with frequencies tunable between 100 GHz and 11 THz. The high power continuous wave (cw) coherent light is observed as a result of quantum tunnelling of electron pairs across the stack of Josephson junctions in the cavity and is tuned by the application of a dc voltage of as small as -1.5 < V_dc (V) < +1.5 through the chip. Here, we present novel approaches towards cavity engineering for the on-chip generation of mm-waves and THz light with circular polarization. We perform numerical simulations/analytical calculations to engineer the cavity geometry and dimensions and compare them with experimental results taken in a cryogenic environment- both at liquid helium and liquid nitrogen temperatures.