TUNABLE PHASE-LOCKING OF STACKED JOSEPHSON FLUX-FLOW OSCILLATORS

A tuning technique for mutual phase locking of two vertically stacked long Josephson junctions is suggested and successfully tested. The tec hnique is based on passing a current through the middle electrode betw een two tunnel barriers. Mutually synchronized oscillation modes in th e Nb/Al-AlOx/Nb stack are found to be tunable in the frequency range f rom 180 to 420 GHz. Presented results extend the possibility of using stacked long Josephson junctions as coherently operating oscillators f or millimeter and submillimeter wave bands. (C) 1996 American Institut e of Physics.