- #1
eahaidar
- 71
- 1
I want to ask how does the wave keep the same amplitude if the wave broadens ?
Thank you for your time
Thank you for your time
Simon Bridge said:The periodicity of the waves means that as the different frequency waves spread out, they will still add up to the same wave shape. But for a pulse, the amplitude does change.
http://www.acs.psu.edu/drussell/Demos/Dispersion/dispersion.html
Simon Bridge said:The pulse is made of traveling sine waves.
The particular mix of sine waves that go to make the pulse is it's spectrum.
In a dispersive media, the different sine waves travel at different speeds - making the pulse change shape - but the mixture is still the same because the individual sine waves go through all space.
But I'd have to see the comment in context to figure what they mean.
The vice versa of "the pulse shape changes while the spectrum stays the same" would be
"the spectrum changes while the pulse shape stays the same"
... for the pulse shape to stay the same, in a dispersive media, the spectrum must change.
Group velocity dispersion (GVD) is a phenomenon that occurs in certain materials or systems where the group velocity of a wave depends on its frequency. This causes different frequencies of the wave to travel at different speeds, resulting in a broadening or distortion of the wave pulse.
GVD is caused by the dependence of the refractive index of a material on the frequency of the light passing through it. This means that different frequencies of light will travel at different speeds, resulting in a dispersion of the wave.
GVD can cause distortion and broadening of optical signals, which can lead to errors in data transmission. It is especially important to control for GVD in high-speed optical communication systems to ensure accurate and reliable data transfer.
One way to measure GVD is through the use of a specialized instrument called an optical spectrum analyzer, which can detect the dispersion of different frequencies of light passing through a material. Other techniques, such as interferometry, can also be used to measure GVD.
One method of compensating for GVD is through the use of dispersion compensating fibers, which are designed to have an opposite dispersion to the material or system causing the dispersion. This allows for the different frequencies of light to be offset and travel at a more uniform speed, reducing the effects of GVD on the wave.