Physical Noise Analysis: High-Speed Photodetectors

This lecture discusses the physical noise analysis in high-speed photodetectors, focusing on the signal-to-noise ratio and various noise sources. It begins with an overview of photon noise and quantum efficiency, explaining how photons are converted into electrons and the impact of internal amplification on noise levels. The instructor elaborates on the processes involved in high-speed digital transmission, detailing how photoelectrons are collected and the effects of load resistance on noise. The lecture also covers KTC noise, which arises from thermal fluctuations, and the noise contributions from amplifiers. The relationship between signal and noise is analyzed, highlighting the importance of understanding the various noise sources, including shot noise and thermal noise. The instructor concludes by comparing scenarios with and without internal amplification, emphasizing the significance of these factors in optimizing photodetector performance. Overall, the lecture provides a comprehensive understanding of the complexities involved in noise analysis for high-speed optical detection systems.