chirped laser pulse

[rashid611]

hi. I want to simulate a chirped laser pulse. can someone help me?

[Status-Mirror]

Hey @rashid611

By "chirped laser pulse", do you mean a laser pulse which has a time-varying wavelength?

In the EPOCH input deck, you can include a laser using a laser block, looking something like this:

begin:laser
   boundary = x_min
   intensity_w_cm2 = 1.0e15
   lambda = 1.06 * micron
   profile = 1.0
   t_profile = gauss(time, 40.0e-15, 40.0e-15)
end:laser

You can set the wavelength to a single number as done above, or you could write it as a time-dependent function using EPOCH maths parser syntax.

For instance, if you wanted the laser wavelength to start at 1.0e-6, and to linearly increase to 2.0e-6 over 100 femtoseconds (remaining fixed at 2.0e-6 after 100fs), you could write:

  lambda = 1.0e-6 + if( time lt 100.0e-15, 1.0e-6 * time/100.0e-15, 2.0e-6)

Hope this helps, Stuart

[rashid611]

Hi STUART. I hope this will work for me.

THANK YOU

[rashid611]

is it possible to simulate the propagation of two, three, or four, ultrashort laser pulses with different foci? For this, what parameter should I change in the laser block?

[Status-Mirror]

Apologies for the delay. See the basic example for a focusing gaussian beam - this tells you how to set up a beam with a specific focal point. For multiple lasers, you can just add more laser blocks to the same simulation.

Hope this helps, Stuart