TheWolf effect (sometimesWolf shift) is afrequency shift in theelectromagnetic spectrum.[1]The phenomenon occurs in several closely related phenomena inradiation physics, with analogous effects occurring in thescattering of light.[2] It was first predicted byEmil Wolf in 1987[3][4] and subsequently confirmed in the laboratory in acoustic sources by Mark F. Bocko,David H. Douglass, and Robert S. Knox,[5] and a year later in optic sources by Dean Faklis and George Morris in 1988.[6]
Inoptics, two non-Lambertian sources that emit beamed energy can interact in a way that causes a shift in the spectral lines. It is analogous to a pair of tuning forks with similar frequencies (pitches), connected together mechanically with a sounding board; there is a strong coupling that results in the resonant frequencies getting "dragged down" in pitch. The Wolf Effect requires that the waves from the sources are partiallycoherent - the wavefronts being partially in phase.Laser light is coherent while candlelight is incoherent, each photon having random phase. It can produce either redshifts or blueshifts, depending on the observer's point of view, but is redshifted when the observer is head-on.[3]
For two sources interacting while separated by a vacuum, the Wolf effect cannot produce shifts greater than thelinewidth of the sourcespectral line, since it is a position-dependent change in the distribution of the source spectrum, not a method by which new frequencies may be generated. However, when interacting with a medium, in combination with effects such asBrillouin scattering it may produce distorted shifts greater than the linewidth of the source.
 | Thisscattering–related article is astub. You can help Wikipedia byadding missing information. |
 | Thisspectroscopy-related article is astub. You can help Wikipedia byadding missing information. |