This paper reviews the state of the art of some new photoncounting detectors. We measured the performance of various commercial silicon, germanium, and InGaAs/InP single-photon avalanche diodes (SPADs) in the 0.8- to 1.55-µm wavelength range. Optimized silicon devices reach 70% quantum efficiency at 800 nm and can work up to 1.1 µm. However, germanium and InGaAs SPADs are sensitive up to 1.4 and 1.6 mm, respectively, with a few percent quantum efficiency. In all samples we measured noise equivalent powers less than 10-15 W/Hz1/2. Compared with vacuum tubes, SPADs have different advantages such as reliability, roughness, low voltage and simple electronic requirements. Furthermore, it is easy to arrange them in the form of arrays, which are required in astronomy and luminescence measurements. Moreover we investigated the performance of a SPAD germanium quad sensor. By using proper driving electronics we avoided optical cross-talk between pixels and we present here the preliminary results of our experiments.