self-defocusing

self-defocusing

[¦self dē¦fō·kə·siŋ]
(optics)
The action of a medium whose index of refraction decreases with increasing optical intensity on a laser beam that is more intense in the center than at the edges, whereby the profile of the refractive index corresponds to that of a negative lens, causing the beam to defocus.
References in periodicals archive ?
The traces reveal a peak followed by valley behaviour that is self-defocusing property for the samples and it is represented by negative nonlinear refractive index [n.
We observed self-focusing and self-defocusing ring patterns with naked eye, which confirms the nonlinear behaviour of the material before conducting the experiment.