An. Obraztsov et al., OPTICAL DIAGNOSTICS FOR FABRICATION OF YBCO THIN-FILM DC-SQUIDS, IEEE transactions on applied superconductivity, 5(2), 1995, pp. 2517-2520
Optical reflectance spectra of thin YBCO films on SrTiO3 bicrystals we
re measured in a photon energy range of 1-3 eV at room temperature. Ra
man spectra measurements in range 200-700 cm(-1) were performed. The b
est samples were shown to have high reflectance anisotropy and well-de
fined peak nu(1)=500+/-1 cm(-1) in Raman spectra. YBCO thin films on b
icrystal substrate that successfully passed optical control were used
for Josephson junctions and dc SQUIDs fabrication. The fabricated dc S
QUIDs operated at 77.3 K in the flux locked loop mode had a typical wh
ite noise (1-2)x10(-5) Phi(0)/Hz(1/2) at frequencies higher than 200-5
00 Hz. The best obtained magnetic field resolution was 650 fT/Hz(1/2)
at frequencies f > 200 Hz.