Microwave Quenching in DC-Biased Coplanar Waveguide Based on ${YBa}_{2}{Cu}_{3}{O}_{7-\delta}$ Thin Film

In this paper, we report on the results of features in the discovered effect of a strong change in the microwave losses (quenching) in HTS-based coplanar waveguide (CPW) at certain values of the input power Pin and direct current (dc) I
_dc
. Two waveguides were studied: CPW-150 and CPW-75, fabricated of epitaxial 150and 75-nm YBCO films. The insertion loss of CPW IL = 10 lg (P
_out
/P
_in
) was measured versus both the operating temperature and the bias dc current I
_dc
when a fixed level of the input X-band pulsed MW signal P
_in
was applied. Here P
_out
is the power measured at the CPW output. A pulse duration Ti was 5 μs with pulse repetition period T = 40 μs. Experiments showed a noticeable difference in specific values of I* = I
_dc
corresponding to the P
_in
-dependent quenching phenomenon in CPW-150 and CPW-75. With a weak input signal, the difference in behavior of CPWs is anticipated, i.e., quenching occurs at a lower current for thinner film. For P
_in
> 1 W the situation is opposite, i.e., quenching for CPW-150 takes place at a lower I*. This is explained by stronger microwave heating of CPW-150.