Photon-number resolving detection techniques with trends towards infrared wavelength

Photon-number resolving detection techniques are reviewed including the principle and its technical requirements, the technical achievement and its trends of development. Three kinds of photon-number resolving detection in development are analyzed: Superconducting transition-edge sensor, charge-integration photon detector and delayed single photon probability mapping based on Avalanche Photodiode. The performance on photon number resolving and the sources of error counts are discussed.