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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.
where is the Planck constant, is the central frequency, is the bandwidth, is the occupation number and is the optical efficiency. The first term is essentially shot noise whereas the second term is related to the bosonic character of photons, variously known as " Bose noise" or "wave noise".
Shot noise as coined by J. Verdeyen [2] is a form of quantum noise related to the statistics of photon counting, the discrete nature of electrons, and intrinsic noise generation in electronics. In contrast to shot noise, [clarification needed] the quantum mechanical uncertainty principle sets a lower limit to a measurement. The uncertainty ...
This noise is known as photon shot noise. [5] Shot noise follows a Poisson distribution, which can be approximated by a Gaussian distribution for large image intensity. Shot noise has a standard deviation proportional to the square root of the image intensity, and the noise at different pixels are independent of one another.
The primary remaining source of noise is photon shot noise from the nominally constant DC level, which is typically dominated by the Local Oscillator (LO). Since the shot noise scales as the amplitude of the LO electric field level, and the heterodyne gain also scales the same way, the ratio of the shot noise to the mixed signal is constant no ...
Photon counting eliminates gain noise, where the proportionality constant between analog signal out and number of photons varies randomly. Thus, the excess noise factor of a photon-counting detector is unity, and the achievable signal-to-noise ratio for a fixed number of photons is generally higher than the same detector without photon counting.
Photon statistics is the ... of light with constant intensity can be modeled by a spatially and temporally coherent electromagnetic wave of a single frequency.
Optical signals have a carrier frequency (about 200 THz and more) that is much higher than the modulation frequency. This way the noise covers a bandwidth that is much wider than the signal itself. The resulting signal influence relies mainly on the filtering of the noise.