TY - JOUR

T1 - Flux-flow-type Josephson oscillator for millimeter and submillimeter wave region. III. Oscillation stability

AU - Nagatsuma, T.

AU - Enpuku, K.

AU - Sueoka, K.

AU - Yoshida, K.

AU - Irie, F.

PY - 1985

Y1 - 1985

N2 - Numerical as well as experimental studies have been made of the oscillation stability for the travelling-wave-type oscillator, which utilizes a vortex motion in a long Josephson junction, i.e., a flux flow. For the Josephson oscillator, a steep current step in a dc I-V characteristic improves the oscillation stability. Two kinds of effects which degrade the steepness of the current step have been investigated for the long junction of the overlap geometry. One is the self-field effect which makes the current step inclined, and the other is the resonant motion of the vortices which induces a staircaselike structure on the current step. We have discussed the method for the reduction of these effects and proposed a novel junction geometry without these effects, i.e., an overlap junction with a projection on one junction side. With the new geometry, we have obtained current steps whose slope is about one hundred times steeper than those obtained with the conventional overlap geometry and whose height attains about a half of the maximum critical current over the wide voltage region 0.1≤Vdc≤1.0 mV. The linewidth calculated from the current step is expected to be a few kHz.

AB - Numerical as well as experimental studies have been made of the oscillation stability for the travelling-wave-type oscillator, which utilizes a vortex motion in a long Josephson junction, i.e., a flux flow. For the Josephson oscillator, a steep current step in a dc I-V characteristic improves the oscillation stability. Two kinds of effects which degrade the steepness of the current step have been investigated for the long junction of the overlap geometry. One is the self-field effect which makes the current step inclined, and the other is the resonant motion of the vortices which induces a staircaselike structure on the current step. We have discussed the method for the reduction of these effects and proposed a novel junction geometry without these effects, i.e., an overlap junction with a projection on one junction side. With the new geometry, we have obtained current steps whose slope is about one hundred times steeper than those obtained with the conventional overlap geometry and whose height attains about a half of the maximum critical current over the wide voltage region 0.1≤Vdc≤1.0 mV. The linewidth calculated from the current step is expected to be a few kHz.

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U2 - 10.1063/1.335643

DO - 10.1063/1.335643

M3 - Article

AN - SCOPUS:0007645493

SN - 0021-8979

VL - 58

SP - 441

EP - 449

JO - Journal of Applied Physics

JF - Journal of Applied Physics

IS - 1

ER -