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Laser Noise

Definition: fluctuations of various parameters of laser light, such as the optical power and phase

More specific terms: intensity noise, phase noise, timing jitter

German: Laserrauschen

Categories: article belongs to category laser devices and laser physics laser devices and laser physics, article belongs to category fluctuations and noise fluctuations and noise


Cite the article using its DOI: https://doi.org/10.61835/2ty

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Due to various influences of quantum noise and fluctuations of various technical origins, the output of a laser always contains some noise. There are different kinds of laser noise:

Origins of Laser Noise

The origins of laser noise can be divided into two groups:

  • quantum noise, in particular associated with spontaneous emission in the gain medium
  • technical noise, arising e.g. from excess noise of the pump source, from vibrations of the laser resonator, or from temperature fluctuations

Impacts of Laser Noise

Laser noise is important for many laser applications. Some examples are:

intensity noise spectrum
Figure 1: Intensity noise spectrum of a solid-state laser.

Methods for Noise Reduction

Laser noise can be reduced in many ways:

  • Quantum noise can be reduced e.g. by increasing the intracavity power level, by minimizing optical losses and by increasing the resonator length.
  • Technical noise influences can be reduced, e.g. by building a stable laser resonator, by temperature stabilization of the setup, or by using a low-noise pump source.
  • Laser parameters can be optimized so that the laser reacts less strongly to certain noise influences.
  • Mode hopping may be suppressed, e.g. with an optical filter.
  • There are various active or passive techniques for the stabilization of lasers.

A prerequisite for effective noise reduction is that the origin of the most disturbing noise is known, in addition to the parameters determining the laser's sensitivity to thus noise influences. Depending on the case, it can be more effective to reduce either noise influences themselves or the laser's sensitivity.

More to Learn

Encyclopedia articles:

Blog articles:


The RP Photonics Buyer's Guide contains four suppliers for laser noise measurement equipment. Among them:


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[7]R. Paschotta et al., “Optical phase noise and carrier–envelope offset noise of mode-locked lasers”, Appl. Phys. B 82 (2), 265 (2006); https://doi.org/10.1007/s00340-005-2041-9
[8]C. J. McKinstrie, “Stochastic and probabilistic equations for three- and four-level lasers: tutorial”, J. Opt. Soc. Am. B 37 (5), 1333 (2020); https://doi.org/10.1364/JOSAB.379976
[9]J. Peng et al., “Principles, measurements and suppressions of semiconductor laser noise – a review”, IEEE J. Quantum Electron. 57 (5), 2000415 (2021); https://doi.org/10.1109/JQE.2021.3093885
[10]C. J. McKinstrie, T. J. Stirling and A. S. Helmy, “Laser linewidths: tutorial”, J. Opt. Soc. Am. B 38 (12), 3837 (2021); https://doi.org/10.1364/JOSAB.439882
[11]C. J. McKinstrie, T. J. Stirling and A. S. Helmy, “Stochastic systems: tutorial”, J. Opt. Soc. Am. B 38 (12), 3818 (2021); https://doi.org/10.1364/JOSAB.439879
[12]R. Paschotta, H. R. Telle, and U. Keller, “Noise of Solid State Lasers”, in Solid-State Lasers and Applications (ed. A. Sennaroglu), CRC Press, Boca Raton, FL (2007), Chapter 12, pp. 473–510
[13]R. Paschotta, “Noise in Laser Technology”. Part 1 – Intensity and Phase Noise; Part 2: Fluctuations in Pulsed Lasers; Part 3: Beam Pointing Fluctuations

(Suggest additional literature!)

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