Peltier Cooling Technique For Single-photon Detector At Infrared Wavelengths

Single-Photon detectors (SPDs) are a key component in a QuantumKey Distribution (QKD) system. So far, the best choice is the separatedabsorption and multiplication InGaAs/InP APD in communicationwavelengths, especially the separated absorption, grading, andmultiplication (SAGM) InGaAs/InP APD. Besides, these APDs have tooperate under the Geiger mode operation to exploit their extremesensitivity. Geiger mode operation can be efficiently realized byworking in gated-mode.Single-photon detector plays an important role in the quantumcryptography communication. The actualities and development ofSingle-photon detector is presented and the importance of temperaturecontrolling in the detecting single photon is analyzed in chapter 1.Chapter 2 describes the microscopic physics of InGaAs/InP APD forsingle-photon detection at infrared wavelengths, including the structureand theory, important characteristics, and the operation mode. Andphotoelectric detectors are introduced in more detail.The dark counts from thermal carriers prominently affect thephoton detection efficiency by using InGaAs/InP avalanche photodiode,which result in the increasing of quantum-bit-error rate. Photoelectronand thermal carriers both are magnified by the APD. So three majorsources of dark counts in InGaAs/InP avalanche photodiode operated inGeiger mode for single photon detection are analyzed to show the waythat can decrease the dark counts and increase the photon detectionefficiency in the Chapter 3, the dark counts from thermal carriers andafter-pulses can be effectively controlled by Peltier cooling and gatedmode operation. Precise temperature control circuit based on ADN8831 has achieved for single-photon detector at infrared communicationwavelengths by using of Peltier cooling. In chapter 4, the measured I-Vcharacteristic curves of different APDs in the several temperatures aregiven. A conclusion that dark noises and avalanche voltage both changewith the temperature is drawn. In the last chapter we discuss the prospectof the present work.