High-temperature superconducting nanowires for photon detection

• Homogeneous YBCO nanowires have been fabricated for photon detection applications.
• Serial-parallel nanowire configuration leads to a large detector active area.
• The YBCO nanowires exhibit critical current densities up to 106 A/cm2.
• The devices have been excited using a 1550-nm wavelength, pulsed laser irradiation.
• Photoresponse signals have been measured and analyzed from 4 K up to the device Tc.

The possible use of high-temperature superconductors (HTS) for realizing superconducting nanowire single-photon detectors is a challenging, but also promising, aim because of their ultrafast electron relaxation times and high operating temperatures. The state-of-the-art HTS nanowires with a 50-nm thickness and widths down to 130 nm have been fabricated and tested under a 1550-nm wavelength laser irradiation. Experimental results presenting both the amplitude and rise times of the photoresponse signals as a function of the normalized detector bias current, measured in a wide temperature range, are discussed. The presence of two distinct regimes in the photoresponse temperature dependence is clearly evidenced, indicating that there are two different response mechanisms responsible for the HTS photoresponse mechanisms.