J. Rothman

Johan Rothman, Salvatore Pes, Pierre Bluet, Julie Abergel, Sylvain Gout, Philippe Ballet Jean-Louis Santailler, Jean-Alain Nicolas, Jean-Pierre Rostaing, Sebastien Renet, Lydie Mathieu, Jérôme Le Perchec
The high gain and low excess noise factor in HgCdTe APDs enables down to single photon detection with a detection efficiency that are expected to exceed 90%. As the detection is done in linear mode these detectors conserve a high dynamic range that enables to detect multi-photon states on a single detector and do not exhibit a dead-time after the detection of one or a number of photons. The latter means that the detection rate is only limited by the bandwidth of the APD and the pre-amplifier, which is why rates in excess of 1 GHz can be achieved in such detectors, surpassing other single photon detection technologies by a factor 10 to 1000. Such high count-rates makes HgCdTe APDs and interesting candidate both for classical free space optical communications and for quantum optics application such as quantum cryptography and quantum computing. The GHz single photon rate landmark has been approached at CEA/Leti by the development of a detection module for deep space FSO in collaboration of ESA. The detection module is a four quadrant HgCdTe APDs, designed to minimize the collection time of the carriers and hybridized to a dedicated CMOS circuit with resistive trans-impedance amplifier (RTIA). The bandwidth and count rate of each channel is limited to 400 MHz by the low noise RTIA. Single photon detection has been demonstrated up to count rates of 500 MHz with such module, implying a cumulated detection rate of 2 GHz if the signal is dispatched over all four quadrants. The aim of this communication is to discuss the expected optimal performance of HgCdTe APDs at GHz count rates in perspective of the most recent results, such as detection efficiency jitter, dark-count rate and maximum count-rate, which have been measured on present detector modules.