InP-Based Single-Photon Detectors and Geiger-Mode APD Arrays for Quantum Communications Applications

To meet the increasing demand from quantum communications and other photon starved applications, we have developed various InP-based single-photon detectors, including discrete single-photon avalanche diodes (SPADs), negative feedback avalanche diodes (NFADs), and Geiger-mode avalanche photodiode (GmAPD) arrays. A large quantity of InP SPADs have been fabricated. Out of similar to 1000 devices with a 25-mu m active area diameter, operated under gated mode at temperature of 233 K, with a pulse repetition rate of 1 MHz and pulse width of 1 ns, the average dark count rate and afterpulsing probability are 30 kHz and 8 x 10(-5), respectively. Smaller (16-mu m active area diameter) and larger (40-mu m active area diameter) discrete devices have been fabricated as well, and their performances are presented along with the 25-mu m diameter devices. NFAD devices can operate in free running mode and photon detection efficiency of similar to 10-15% can be achieved without applying any hold-off time externally. When the temperature decreases from 240 to 160 K, the noise equivalent power (NEP) decreases from 1.9 x 10(-16) to 1.8 x 10(-18)WHz(-1/2), with the activation energy being 0.2 eV. The very low NEP at similar to 160 K makes NFAD devices an ideal choice for long distance, entanglement-based quantum key distributions. GmAPD arrays provide an enabling technology for many active optical applications, such as 3-D laser detection and ranging (LADAR) and photon starved optical communications. Both 32 x 32 and 128 x 32 GmAPD arrays have been fabricated with high performance and good uniformity. GmAPD focal plane arrays (FPAs) with framed readout mode have enabled very high-performance flash LADAR systems. GmAPD FPAs with asynchronous readout mode will enable high rate quantum key distributions and other quantum communications applications.