(a) Photograph of circuit (see Table I) and (b) its corresponding cross-section drawing (not to scale). The junctions are made out of a trilayer, patterned using a self-aligned process, where the upper Nb layer (“Nb 2”) is removed by RIE around the junction mesas and replaced by SiO. A Nb counter electrode (“Nb 3”) is then sputtered to contact junctions and make the Nb/SiO/Nb rf tuning microstrip circuit. Designed for broadband submillimeter-wave SIS mixing, it is also a nonuniform DJTL or SQUIG.
Schematic of the 2D model used to investigate nonuniform DJTLs. See Table III.
Comparison of curves, plotted in normalized units, between the magnetic approximation and solution of Eq. (9) (with implicit curve method). The device is in inline current feed, uniform geometry with 11 junctions, , . From the left to the right, takes successively the values 0.1, 0.2, and 0.5. When , curves are very close to magnetic approximation. For the model becomes a discretization of a long junction device.
Measured and simulated in the state vs at 4.2 K for the arrays , , and . For best fit the device was simulated with one junction of area and the other of area .
Simulated curves for the nonuniform DJTL consisting of five junctions . For “triangle” curve, junctions are located at (in ), , , , , and with respective junction areas (in ): 0.24, 2.24, 4.96, 2.24, 0.24. For “pulse” curve, , , and respective junction areas: 0.66, 2.4, 3.5, 2.4, and 0.66.
Nonuniform DJTL geometry (all dimensions in ).
Lumped elements per unit surface in the 2D-model of the DJTL (see Fig. 2 and Table II)
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