Frequency Stabilization of X-Band Sources for Use in Frequency Synthesis into the Infrared

An X-band source of excellent frequency stability is needed in infrared frequency multiplication of high order. Such a source has been used in frequency multiplication by a factor of 401 using a point-contact Josephson junction as a frequency multiplier and mixer. Noise data on three X-band systems are reported. Two of these systems use klystrons as the source of X-band power; the other uses a Gunn oscillator. Each of these three systems employs both cavity and injection stabilization. Injection stabilization, using a quartz-oscillator-driven multiplier chain, provides the second-to-second and minute-to-minute stability needed for the Josephson junction experiment. To our knowledge, this is the first published noise data where cavity and injection stabilization are simultaneously employed. The quality of the best system reported here is much better-both around 1 Hz from the carrier and around 50 kHz from the carrier-than the source used to multiply by a factor of 401 to 3.8 THz.