Princeton Lightwave Inc. has introduced indium phosphide single-photon-counting avalanche photodetectors that reach peak responsivity at 1.06 μm, enabling very low dark count while providing an order of magnitude larger detection efficiency compared with silicon devices. They can achieve a detection efficiency of 50 percent, according to the company. Available in diameters of 80 and 200 μm, the instruments are packaged with a thermoelectric cooler inside a windowed TO-8 can. The low dark count rate allows operations in gated or nongated mode. Applications include low-light YAG laser detection, free-space optical transmission, time-resolved spectroscopy in the biomedical field, and lidar and ladar systems for remote sensing.