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Nguyên tắc cơ bản của lượng tử ánh sáng P17

Simkon Poisson (1781-1840) developed the probability distribution that describes photodetector noise. A photodetector is a device that measures photon flux or optical power by converting the energy of the absorbed photons into a measurable form. | Fundamentals of Photonics Bahaa E. A. Saleh Malvin Carl Teich Copyright 1991 John Wiley Sons Inc. ISBNs 0-471-83965-5 Hardback 0-471-2-1374-8 Electronic CHAPTER SEMICONDUCTOR PHOTON DETECTORS 17.1 PROPERTIES OF SEMICONDUCTOR PHOTODETECTORS A. Quantum Efficiency B. Responsivity C. Response Time 17.2 PHOTOCONDUCTORS 17.3 PHOTODIODES A. The p-n Photodiode B. The p-i-n Photodiode C. Heterostructure Photodiodes D. Array Detectors 17.4 AVALANCHE PHOTODIODES A. Principles of Operation B. Gain and Responsivity C. Response Time 17.5 NOISE IN PHOTODETECTORS A. Photoelectron Noise B. Gain Noise C. Circuit Noise D. Signal-to-Noise Ratio and Receiver Sensitivity Heinrich Hertz 1857 1894 discovered photoemission in 1887. Simeon Poisson 1781-1840 developed the probability distribution that describes photodetector noise. 644 A photodetector is a device that measures photon flux or optical power by converting the energy of the absorbed photons into a measurable form. Photographic film is probably the most ubiquitous of photodetectors. Two principal classes of photodetectors are in common use thermal detectors and photoelectric detectors Thermal detectors operate by converting photon energy into heat. However most thermal detectors are rather inefficient and relatively slow as a result of the time required to change their temperature. Consequently they are not suitable for most applications in photonics. The operation of photoelectric detectors is based on the photoeffect in which the absorption of photons by some materials results directly in an electronic transition to a higher energy level and the generation of mobile charge carriers. Under the effect of an electric field these carriers move and produce a measurable electric current. We consider only photoelectric detectors in this chapter. The photoeffect takes two forms external and internal. The former process involves photoelectric emission in which the photogenerated electrons escape from the material as free electrons. In .