Dynamic range of frequency-selective response of high-Tc Josephson detector to millimeter-wave radiation

We have studied a voltage dependence of the response ΔI(V) of high-T_c Josephson detector to millimeter-wave radiation as a function of power of incident radiation. YBa₂Cu₃O_7-x grain-boundary junctions with the resistances R_n=0.5-1.5 Ohm and the I_cR _n-product in the range 0.16-0.25 mV at 80 K have been fabricated for this study. Gunn oscillator with the frequency f=86 GHz and a set of calibrated attenuators with total attenuation of 80 dB have been used for the measurements. The dynamic range, i.e. the range of power of electromagnetic radiation at which the response of the detector is directly proportional to radiation power, was found to be around 40 dB above the noise-equivalent power for frequency-selective response at voltages V near hf/2e and >45 dB for the broadband response at low voltages