File:Dispersion pulse.gif

From Wikimedia Commons, the free media repository
Jump to navigation Jump to search

Dispersion_pulse.gif(576 × 189 pixels, file size: 1.5 MB, MIME type: image/gif, looped, 61 frames)

Captions

Captions

Diagram of how different velocities of the Fourier components distort and stretch a pulse.

Summary[edit]

Description
English: Any pulse can be thought as the superposition of sinusoidals If all sinusoidals travel at the same speed, the pulse will propagate without changing shape. But if different frequencies travel at different speeds, the pulse will be distorted (dispersion).
Date
Source https://twitter.com/j_bertolotti/status/1189524047538855936
Author Jacopo Bertolotti
Permission
(Reusing this file)
https://twitter.com/j_bertolotti/status/1030470604418428929

Mathematica 11.0 code[edit]

g1 = Sum[(E^(I k x) E^(-(k - k0)^2/(2 \[Sigma]^2)) E^(-I (c k) t)) /. {\[Sigma] -> 1, k0 -> 4, c -> 1}, {k, 0, 10, 0.05}];
g2 = Sum[(E^(I k x) E^(-(k - k0)^2/(2 \[Sigma]^2)) E^(-I (Sqrt[2 c^2 k^2 + \[Omega]p^2 - Sqrt[4 c^4 k^4 + \[Omega]p^4]]/Sqrt[2]) t)) /. {\[Sigma] -> 1, k0 -> 4, c -> 1, \[Omega]p -> 5}, {k, 0, 10, 0.05}];
p1 = Table[
   GraphicsRow[{Plot[
      Evaluate@Join[{Re[g1]/25}, Evaluate@Table[Re[(E^(I k x) E^(-(k - k0)^2/(2 \[Sigma]^2)) E^(-I (c k) t) - k) /. {\[Sigma] -> 1, k0 -> 4, c -> 1}], {k, 2, 6, 1}] ], {x, -3, 40}, 
      PlotStyle -> {Black, Purple, Orange, Cyan}, Axes -> False, PlotRange -> {-6.5, 2.1}, PlotLabel -> "Non dispersive", LabelStyle -> {Black, Bold}]
     ,
     Plot[
      Evaluate@Join[{Re[g2]/25}, Evaluate@Table[Re[(E^(I k x) E^(-(k - k0)^2/(2 \[Sigma]^2)) E^(-I (Sqrt[2 c^2 k^2 + \[Omega]p^2 - Sqrt[4 c^4 k^4 + \[Omega]p^4]]/Sqrt[2]) t) - k) /. {\[Sigma] -> 1, k0 -> 4, c -> 1, \[Omega]p -> 5}], {k, 2, 6, 1}] ], {x, -3, 40}, PlotStyle -> {Black, Purple, Orange, Cyan}, Axes -> False, PlotRange -> {-6.5, 2.1}, PlotLabel -> "Dispersive",  LabelStyle -> {Black, Bold}]}, ImageSize -> Large]
   , {t, 0, 30, 0.5}];
ListAnimate[p1]

Licensing[edit]

I, the copyright holder of this work, hereby publish it under the following license:
Creative Commons CC-Zero This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.
The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current10:07, 31 October 2019Thumbnail for version as of 10:07, 31 October 2019576 × 189 (1.5 MB)Berto (talk | contribs)User created page with UploadWizard

Metadata