Wideband THz detectors based on YBCO thin films at 77K and at room temperature

Paper in proceeding, 2011

We present results of experimental investigation of THz direct detectors based on ultrathin YBCO films. The detectors are integrated with a spiral planar antenna. In the frequency band of 0.1-1.6THz the optical responsivity is from 170V/W for 77K. It increases to 400 V/W for operation temperature about 76K. The responsivity was constant up to 100kHz. Using mixing technique, the measured time constant is 0.5-2ns. Currently, at 77K, the NEP is 20pW/Hz0.5. At room temperature, the NEP is about 250pW/Hz0.5. For the same devices as coherent detector, the mixer gain was -21dB at 77K (and -28dB) at room temperature for an LO power of 0.4mW. With the present devices a mixer gain of up to -23dB is possible at 300K for an LO power of 1.5mW. Using smaller devices, similar gain can be achieved for a much smaller LO power.