Spatially resolved microwave field distribution in YBaCuO disk resonators visualized by laser scanning

The applicability of superconducting films in high-performance microwave de vices suffers from inhomogeneous growth and local defects. Therefore we hav e installed a laser scanning system to visualize with spatial resolution th e distribution of the microwave fields in 2-in.-diam YBaCuO disk resonators . The TM310 mode was imaged at a loaded quality factor of 8.3 x 10(4) via c hanges of the resonant frequency at 2.21 GHz and 40 K. The field distributi on agreed with a magnetic-wall model, indicating at the contour of the disk fringe fields, but without strong edge enhancement. The data also indicate d an inhomogeneous effective microwave penetration depth. The spatial resol ution is presently limited to about 2 mm by heat diffusion. (C) 1998 Americ an Institute of Physics. [S0003-6951(98)02449-8].