Microscopic Imaging of RF Current Distribution and Intermodulation Sources in Superconducting Microwave Devices

We have developed a new version of the Laser Scanning Microscope (LSM) that images changes in the third-order intermodulation (IM) signal as a laser-spot perturbation is scanned over the sample. We directly image the regions of maximum IM generation in a meandering microstrip resonator, and compare them to the simultaneously measured RF current distribution.