I am interested to compare the temporal dispersion of 6fs,18 fs and 30fs pulses in glass (like BK7).
I think 6fs will spread to be about 30 fs if pass through 1 mm and about 56 fs if pass through the 2 mm of Bk7.
For 18 fs , it will be 22 fs if pass through 1 mm and about 24 fs if pass through the 2 mm of Bk7.
For 30 fs , it will be 31 fs if pass through 1 mm and about 32fs if pass through the 2 mm of Bk7.
What is your opinion and if you have some related papers please?
The dispersive pulse broadening for Gaussian pulses can be calculated with the following formula
tout = tin sqrt( 1+ 7,7 D2/tin4)
tout FWHM pulse duration after the material
tin FWHM pulse duration of the bandwidth limited input pulse
For 800nm and BK7 glass b = 500fs2/cm and D = b L L.. propagation length in the material
This formula considers only second order dispersion (group delay dispersion). and proivdes and estimation of the pulse duration. For a more precise calculation you have to Fourier transform the pulse, mulltiply it with the spectral phase and transform it back. However for a rough estiamation and compariosn the above mentioned formula should be fine.
Thanks a lot Dr. Christian for that answer.
Would you please, give me a reference about that equation and can it be valid for few cycle pulses? i.e. 5 fs or so?
Details can be found e.g.
J.C Diels and W. Rudolph "Ultrashort Laser Puse Phenomena" Academic Press
G. P Agrawal "Nonlinear Fiber Optics" Academic Press (here also the role of third order disperison is discussed and analytical formulas are given)
Teh formula hold even for few cycle pulses, as long as it is allowed to describe the pulse by an envelope and a carrier wave, which is the case for a 5fs pulse at 800nm. A detailled discussion about the validity of this approximation can be found e.g. in
Brabec and Krausz "Intense few-cycle laser fields: Frontiers of nonlinear optics" Rev. Mod. Phys. 72, 545 (2000)
Thanks a lot again for these references.
The paper is very important and covered many issues in almost 50 pages!
For the paper, I think I did not find the equation. Maybe, I missed it. Here I have attached it. Would you please highlight that equation for me if possible.
I think I found your equation finally and I will try to calculate the group delay dispersion GDD for every dispersive medium I will use. But I wonder how the GDD will vary with the bandwidth of the input pulse?
For other readers looking for more information, see the similar question posted at the link below.
https://www.researchgate.net/post/What_is_the_difference_between_temporal_dispersion_of_6fs_18_fs_and_30fs_Gaussian_pulses_in_glass
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