Ebook: Single Photon Detection for Data Communication and Quantum Systems

The era of photodiode integrated circuits (PDICs) started in the 1990s with their application in audio CD players, CD-ROMs, and DVD systems; this occurred because the bandwidths and transimpedance of optical sensors consisting of discrete photodiodes/photodiode arrays and amplifier integrated circuits (ICs) reached a limit at that time. Since then, rapid progress has been made in the bandwidth/data rate and quantum efficiency/responsivity of integrated photodiodes and sensor ICs. The first quantum leap was the integrated p–intrinsic–n photodiode. Avalanche photodiodes (APDs) in the linear mode then introduced the second step in performance gain. The newest quantum leap in integrated photodetectors took the form of APDs operated in the Geiger mode, in which the detection of single photons is possible.

Integrated photodiodes not only allowed increased bandwidth and transimpedance gains; they were essential for image sensors with high and very high numbers of pixels. Integrated photodiodes offered better immunity to electromagnetic interference, improved reliability, and, last but not least, they reduced the costs of many optical sensors.

Single-photon detection has been the subject of huge publicity in the research field for more than a decade; much progress has been made using single-photon avalanche diodes (SPADs) integrated into complementary metal–oxide–semiconductor (CMOS) chips. Many publications cover the topics of SPADs and SPAD sensor ICs for biomedical applications, imaging, and distance measurement/three-dimensional sensors. Publications on the use of integrated SPADs for quantum communications, quantum cryptography, and quantum computer applications seem to be underrepresented. In addition, there is a new trend toward SPAD-based optical receivers for data and free-space communications. This book will therefore focus on the use of SPAD ICs in data communications and quantum systems.