This book represents a major investigation on the properties of Superconducting Nanowire Single Photon Detectors (SNSPDs). In this edition, measurement of temperature of two dimensional or a three dimensional structures using SNSPDs by Coherent Raman Scatterings (both stokes and anti-stokes) and also finding the faults in the fiber optic communication cable and the fault location is reported. The book presents a key technology for single-photon measurements and applications in the optical and near-infrared region.