Fig. 4.

Temporal profiles obtained with the WSi SNSPD illuminated by scattered light pulses from a nanosecond (empty squares) and a picosecond laser (filled squares). Both lasers emit at $\lambda =4.9\text{μm}$. The laser intensities were heavily attenuated so that much less than one photon per pulse was detected. The measured laser profiles (100 ps/point) are fitted with Gaussians (black solid lines) to yield the FWHM values. The picosecond laser pulse has a specified FWHM ≈30 ps. The inset graph shows the response time of the InSb detector to the scattered nanosecond laser pulse.