Abstract

Previously we reported on a picosecond electro-optic sampling system used to characterize superconducting Josephson devices.¹ A block diagram is shown in Figure 1. The sampler was driven by a colliding-pulse mode-locked laser which produced two 120 fs FWHM pulses at 100 MHz. One pulse was used to generate an electrical signal of adjustable height and width, via a photoconductive switch. This signal was used to excite the test device placed in the cryogenic environment. The resultant electrical transient was then sampled with the second optical pulse using a birefringent lithium tantalate crystal. By changing the relative delay between the optical excitation and sampling pulses, the temporal development of the electrical transient was recorded using conventional slow speed electronics. The limitations on system response were found to be due to the long cables required to move signals into, and out of, the cryogenic environment.

© 1985 Optical Society of America