Submillimeter Quasioptical Josephson Junction Oscillator with Integrated Tuning Elements.

摘要

The goal of this program was to demonstrate a Quasioptical Josephson Oscillator with Integrated Tuning Elements using standard Conductus niobium technology. This device is based on a novel approach that incorporates integrated tuning and impedance-matching structures at every Josephson junction/antenna pair. The device has been designed, fabricated and successfully tested. A new, unit cell has been devised, incorporating a sub-array of 1 to 16 Josephson junctions. Microstrip transformers are used locally between each sub-array and its antenna. The oscillator with 110 Josephson junctions and bow-tie antennas was found to radiate close to its maximum available power at 115 GHz. The on-chip SIS radiation detector has detected 2.64 nW of power. The oscillator was tuned across 19 GHz, or 16% of fractional bandwidth, in reasonable agreement with the predicted value of 19%. This is the first demonstration of a distributed array Josephson oscillator, where each junction feeds its own antenna and phase-locks to the radiation of other junctions. It is also the first demonstration of using integrated microstrip tuning and impedance matching elements at every Josephson junction of an oscillator. Finally, this is the first distributed Josephson oscillator reported to date that appears to radiate close to its maximum available power. Submillimeter, Oscillators, Antenna arrays, Superconducting electronics, Quasioptical.