Imaging sub-millimeter waves in planar cryoelectronic circuits by scanninglaser microscopy

Low temperature scanning laser microscopy (LTSLM) is demonstrated to be cap able of imaging sub-THz electromagnetic fields in cryoelectronic integrated structures. This method allows one to evaluate the spatial distribution of time-averaged field amplitudes with a resolution of about one micrometer f or samples with characteristic dimensions of order millimeters. Using LTSLM , cryoelectronic devices with both passive and active superconducting eleme nts can be characterized. Local heating of superconducting structures by a laser beam introduces extra loss for the propagating and standing sub-milli meter waves. We present LTSLM images of two-dimensional 400 to 500 standing GHz wave patterns in integrated superconducting receiver chips.