2
$\begingroup$

In some cases, according to Wikipedia, the envelope of a gaussian beam can go faster than speed of light hence leading to superluminal group velocity. However, the signal/energy still propagates at subluminal speed which is seen from the speed of the rising front of the pulse.

Do you know a practical example for which this situation arises? Is it possible to have a interactive picture of the corresponding wave?

I presume the pulse should distort quite significantly.

$\endgroup$
0
$\begingroup$

Superluminal group velocity can occur in near absorption peak, known as regions of anomalous dispersion. So-called "superluminal tunneling" experiments have bee conducted in thes regions, but when carefully analyzed there is no information transferred faster than light.

Some references are given here: https://www.rp-photonics.com/superluminal_transmission.html

I'm not familiar with any applications, but everything is good for something, certainly strong absorption lines are useful.

$\endgroup$
  • $\begingroup$ That's a good information ! "Propagation of a Gaussian Light Pulse through an Anomalous Dispersion Medium" gives the form of the pulse as a function of time at different points in space. Distorsion is seen as pulse narrowing and broadening depending on super/sub luminal regime. I presume such effects may also arise in the context of non linear optics .. $\endgroup$ – Ronan Tarik Drevon Feb 29 '16 at 11:43
  • $\begingroup$ Nonlinear optics is a broad field, of which I use a small part; ask a specific question andd $\endgroup$ – Peter Diehr Feb 29 '16 at 12:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.