Electrical and thermal modulation of the propagation time in superconducting spiral lines by optoelectronic techniques

Current and temperature controlled delays in the propagation time of electrical pulses in YBa₂Cu₃O_7-x (YBCO) spiral transmission lines have been investigated by using optoelectronic techniques. The transmission lines are configured in a stripline geometry, where the central strip consists of a thin film of YBCO embedded in LaAlO₃. The propagation time of electrical pulses through the spiral transmission lines is measured using electrical autocorrelation techniques making use of semiconductor optical switches. The measured propagation time shows a quadratic dependence on the applied current, which is in good agreement with the Ginzburg-Landau theory. As the temperature increases, a gradual increase in pulse width and a delay in the propagation time of electrical pulses are observed. The results are used to determine the actual temperature-dependent function of the magnetic penetration depth of YBCO spiral lines