Gordo, Paulo Romeu SeabraAbreu, Manuel AdlerPinto, Rafael Alexandre Gomes2024-02-202024-02-2020232023http://hdl.handle.net/10451/62746Tese de mestrado, Engenharia Física, 2023, Universidade de Lisboa, Faculdade de CiênciasThe presented dissertation explores the manufacturing process of a vacuum chamber designed for the purpose of evaluating and comparing the performance of two avalanche photodiodes operating in both linear and Geiger-mode regions for single photon counting across various temperature states and NIR1 optical emission power modes. The research encompasses the design, construction, and comprehensive testing of a mini-test chamber capable of accommodating two sensors simultaneously, covering mechanical, optical, and electrical aspects. Throughout the conducted experiments, the chamber demonstrated its ability to maintain a stable vacuum environment of up to 9.4 Pa while offering precise temperature control within the range of 333 K to 244 K, safely supplied with up to 15 A and 200 V. This setup facilitated the characterization and comparison of one of the photodiodes under four distinct temperature conditions: 291.95 K, 270.15 K, 253.95 K, and 249.55 K, with the injected optical power varied in both continuous wave and pulsed modes. To directly assess the response of the sensors, two readout circuits were chosen as optimal solutions. The first was a transimpedance amplifier2 circuit, which facilitated the study of the photodiode’s behavior in the linear mode, below the breakdown voltage. By leveraging its gain, current values in this region could be accurately measured, allowing for detections as low as 3 × 10−9 A and achievable gains of up to 300 with a signal-to-noise ratio of 112 dB. The second was a passive quenching circuit, focused on examining the photodiode’s operation in the Geiger-mode region, above the breakdown voltage. By operating the sensor within the entire workable reverse bias range, the impact of the quenching resistor could be investigated. This circuit achieved gains of up to 600 and a photon detection rate (PDR) of up to 5.6 MHz with a minimum terminal capacitance of 3.7 × 10−12 F. Additionally, AC/DC polarization was applied to the sensor to explore the impact of a wave time-changing biasing.engLiDARSensores para InfravermelhoAPD e SPADModo Linear e GeigerCâmara de Testes de VácuoTeses de mestrado - 2023master thesis203490940