RP Photonics

Encyclopedia … combined with a great Buyer's Guide!

VLib
Virtual
Library

Frequency Noise

Definition: noise of the instantaneous frequency of an oscillating signal

German: Frequenzrauschen

Category: fluctuations and noise

How to cite the article; suggest additional literature

The term frequency noise refers to random fluctuations of the instantaneous frequency of an oscillating signal. The instantaneous frequency is defined as

instantaneous frequency

i.e. essentially as the temporal derivative of the oscillation phase φ. Any random deviation from a purely linear phase evolution is seen as frequency noise.

The power spectral density of frequency noise (with units of Hz2/Hz) is directly related to that of the phase noise:

power spectral density of frequency noise

where f is the noise frequency. For example, white frequency noise (Sν(f) = const) corresponds to phase noise with a power spectral density proportional to f−2. In that case, the linewidth is π times the one-sided power spectral density of the frequency noise (or 2π times the two-sided power spectral density). Such a situation occurs e.g. in a single-frequency laser which is only subject to quantum noise and exhibits the Schawlow–Townes linewidth.

Phase noise or frequency noise are just different ways of describing the same phenomenon. However, numerical processing of frequency noise rather than phase noise can have technical advantages in certain situations.

See also: phase noise, power spectral density, linewidth, laser noise, coherence, coherence time
and other articles in the category fluctuations and noise

How do you rate this article?

Click here to send us your feedback!

Your general impression: don't know poor satisfactory good excellent
Technical quality: don't know poor satisfactory good excellent
Usefulness: don't know poor satisfactory good excellent
Readability: don't know poor satisfactory good excellent
Comments:

Found any errors? Suggestions for improvements? Do you know a better web page on this topic?

Spam protection: (enter the value of 5 + 8 in this field!)

If you want a response, you may leave your e-mail address in the comments field, or directly send an e-mail.

If you enter any personal data, this implies that you agree with storing it; we will use it only for the purpose of improving our website and possibly giving you a response; see also our declaration of data privacy.

If you like our website, you may also want to get our newsletters!

If you like this article, share it with your friends and colleagues, e.g. via social media:

arrow