Detecting properties of YBaCuO thin film bridges

A study is made of the properties of YBaCuO superconducting microbridges. They were fabricated by both direct photolithographic techniques and focused laser beam patterning. The YBaCuO thin films were deposited onto ZrO/sub 2/, MgO, and SrTiO/sub 3/ substrates by laser ablation of a massive YBaCuO target. The Josephson effect was observed in the bridges by detecting Shapiro steps and selective responses under irradiation with a signal frequency of 27-36 GHz. The value of the product I/sub c/R/sub N/ reached 4.5 MV at T=4.2 K and 420 mu V at T=77 K. The best values for wideband sensitivity eta (T) and noise-equivalent power NEP(T) were eta (77)=5*10/sup 3/ V/W NEP(77)=2*10/sup -12/ W/Hz/sup 1/2/ eta (20)=2.5*10/sup 6/ V/W, and NEP(20)=10/sup -14/ W/Hz/sup 1/2/. The estimation of noise by the width of the selective response shows than the internal noise is 1.5-2.5 times higher than the thermal value.