Superconducting single-photon detectors (SSPD) allowed us to conduct photon-counting experiments with very broad continuous spectral coverage from 0.4 till 2.5 microns. We discuss several advantages this new technology brings in telecommunication area of spectrum. The major impact can also be seen in the area of biomedical applications where using very low level of infrared light enable us to avoid any disturbance of the object under investigation.