| Detecting light has historically played an important role in the development of our scientific understanding and modern technologies, and sensing low light levels is important for applications in many diverse fields including quantum communications and computing. The most practical method of detecting single photons in the near infrared uses indium gallium arsenide and indium phosphide avalanche photodiodes (InGaAs/InP APD's). This thesis presents the design, construction and characterization of a 200 MHz gated single-photon detector (SPD) based on an InGaAs/InP APD and the self-differencing electronic post-processing technique. Our design features fully integrated components that are all home-made or commercially available on printed circuit boards (PCBs), and shows promise to be miniaturized with full implementation on a PCB. The detector was used to characterize a high-rate spontaneous parametric downconversion (SPDC) source of photon pairs; as well, we have used the detector with our 100 MHz clocked quantum key distribution (QKD) system, thereby removing a major bottleneck towards high secret key rates. |
