Properties of Cascade Switch Superconducting Nanowire Single Photon Detectors

Superconducting nanowire single photon detectors have been realized using an innovative photon induced cascade switch of parallel nanowires. We demonstrate that this configuration allows, at the same time, a fast response and a large active area, with the additional advantage of signal pulses with a larger signal to noise ratio. These improvements are obtained maintaining the good quantum efficiency of traditional meandered superconducting detectors. We show that due to the high speed of the parallel nanowire detector special attention is needed to avoid latching, a phenomenon which in the parallel nanowire detector degrades the detector efficiency. We describe how the latching problem can be avoided using a proper nanowire configuration.