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Lecture

Noise in Optical Receivers

In course

EE-440: Photonic systems and technology

The physics of optical communication components and their applications to communication systems will be covered. The course is intended to present the operation principles of contemporary optical communication systems employing optical fibers and modern op ...

Description

This lecture covers the different types of noise present in optical receivers, starting with shot noise generated by random electron generation. It explains how shot noise variance is calculated and how dark current contributes to it. The lecture also delves into thermal noise caused by random electron motion in resistors, discussing its power spectral density and variance. It then explores the signal-to-noise ratio for p-i-n diodes, detailing the total noise variance and defining SNR. The presentation concludes by comparing thermal and shot noise limits, discussing noise in APD receivers, and analyzing SNR in APD compared to p-i-n diodes.

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Instructor

Camille Sophie Brès

Prof. Camille-Sophie Brès is an Associate Professor in the Institute of Electrical Engineering within the School of Engineering of EPFL. Her primary research interests are centered optical communications and on parametric and nonlinear processes in optical fiber and non-silica platforms for ultrafast signal processing, all optical networks, sensing and light sources. She has authored over thirty peer-reviewed journal articles and has presented more than 15 papers at international conferences. She received the Gordon Wu Fellowship for her graduate studies, the NSF CIANs Diversity Postdoctoral Fellowship in 2009, the Early Career Woman in Engineering Award in 2016. She is a senior member of the IEEE and OSA. 2019 - present: Associate Professor in the Institute of Electrical Engineering, EPFL 2011 - 2018: Assistant Professor in the Institute of Electrical Engineering, EPFL 2010 - 2011: Assistant Project Scientist, University of California San Diego (UCSD) 2007 - 2010: Postdoc in ECE, University of California San Diego (UCSD) 2002 - 2007: Ph.D in Electrical Engineering, Princeton University 1998 - 2002: B.Eng with Honours in Electrical Engineering, McGill University

Official source

Ontological neighbourhood

Information engineering

Signal processing: Digital image processing

Related concepts (21)

Noise (electronics)

In electronics, noise is an unwanted disturbance in an electrical signal. Noise generated by electronic devices varies greatly as it is produced by several different effects. In particular, noise is inherent in physics and central to thermodynamics. Any conductor with electrical resistance will generate thermal noise inherently. The final elimination of thermal noise in electronics can only be achieved cryogenically, and even then quantum noise would remain inherent. Electronic noise is a common component of noise in signal processing.

Shot noise

Shot noise or Poisson noise is a type of noise which can be modeled by a Poisson process. In electronics shot noise originates from the discrete nature of electric charge. Shot noise also occurs in photon counting in optical devices, where shot noise is associated with the particle nature of light. In a statistical experiment such as tossing a fair coin and counting the occurrences of heads and tails, the numbers of heads and tails after many throws will differ by only a tiny percentage, while after only a few throws outcomes with a significant excess of heads over tails or vice versa are common; if an experiment with a few throws is repeated over and over, the outcomes will fluctuate a lot.

Johnson–Nyquist noise

Johnson–Nyquist noise (thermal noise, Johnson noise, or Nyquist noise) is the electronic noise generated by the thermal agitation of the charge carriers (usually the electrons) inside an electrical conductor at equilibrium, which happens regardless of any applied voltage. Thermal noise is present in all electrical circuits, and in sensitive electronic equipment (such as radio receivers) can drown out weak signals, and can be the limiting factor on sensitivity of electrical measuring instruments.

Noise figure

Noise figure (NF) and noise factor (F) are figures of merit that indicate degradation of the signal-to-noise ratio (SNR) that is caused by components in a signal chain. These figures of merit are used to evaluate the performance of an amplifier or a radio receiver, with lower values indicating better performance. The noise factor is defined as the ratio of the output noise power of a device to the portion thereof attributable to thermal noise in the input termination at standard noise temperature T0 (usually 290 K).

Noise (signal processing)

In signal processing, noise is a general term for unwanted (and, in general, unknown) modifications that a signal may suffer during capture, storage, transmission, processing, or conversion. Sometimes the word is also used to mean signals that are random (unpredictable) and carry no useful information; even if they are not interfering with other signals or may have been introduced intentionally, as in comfort noise. Noise reduction, the recovery of the original signal from the noise-corrupted one, is a very common goal in the design of signal processing systems, especially filters.

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