Jc. Booth et al., 3RD-ORDER HARMONIC-GENERATION IN HIGH-TEMPERATURE SUPERCONDUCTING COPLANAR WAVE-GUIDES AT MICROWAVE-FREQUENCIES, Applied superconductivity, 5(7-12), 1997, pp. 379-384
We use third-harmonic measurements of coplanar waveguide (CPW) transmi
ssion lines to explore the behavior of nonlinearities in microwave dev
ices fabricated from high-T-c superconductors. Our measurements focus
on the effect of varying the CPW geometry, including center conductor
linewidth, line length, and film thickness, on the nonlinearity of the
transmission line circuit as measured by the third-order intercept. T
he third-order intercepts decrease (indicating more nonlinearity) with
increasing line length for all geometries studied. Also, differences
in the third-order intercepts between lines of different linewidth and
film thickness can be explained quantitatively by appropriately scali
ng the incident microwave power. These observations demonstrate that t
he sources of nonlinearity in our CPW transmission lines are distribut
ed along the line length, and depend on the detailed form of the curre
nt distribution within the superconductor. Published by Elsevier Scien
ce Ltd.