About the electric field generated after the laser is over?

[feelingxxxxxxx]

dear sir,
My laser is Gaussian on a time scale, but after my laser is over, there is still an electric field coming out. What happens?
!Thank you for your answer and have a good life.

[Status-Mirror]

Hey @feelingxxxxxxx,

I'm not sure what your line-out plot is showing, as these images are cropped. Is this a Bz line-out averaged over the y direction? I don't think this is a good measure as a vertical line captures the wings at high and low y. If you instead plotted the fields in cells along y=0, I think you would see a cut-off in the fields similar to the one you expect.

I think it's easier to explain in your full Bz dump. I can see your main pulse, and some small oscillations following behind. This could be a 2D version of the suprious oscillations shown at the bottom of our laser deck page. These occur when you use a t_end in your laser block.

Alternatively, this could be a physical spreading-out of your pulse?

Hope this discussion helps,
Stuart

[feelingxxxxxxx]

Hey @Status-Mirror,
Thanks for your answer, is there any way to eliminate this little shock after t-end?

[Status-Mirror]

The laser deck documentation seems to suggest that discontinuities in the profile can drive shocks. You could try removing the t_end key, and just let the pulse decay according to a Gaussian distribution?

The wings may still persist though. If they're driven by numerical issues, then you could reduce them by making your cell-size smaller?

It's possible the shocks you're seeing are related how Gaussian beams propagate in this kind of grid though, so you might find that the above tricks don't work.

[feelingxxxxxxx]

Dear sir,
I found that the vibration was driven by numerical problems. The above 2 figures were obtained by me at -min with the laser focus spot and were correct. The tiny vibration is due to the fact that I changed the laser focal spot setting according to the template you provided. Could you please help me check where the setting of my laser code is wrong?

[Status-Mirror]

Would it be possible for you to copy and paste your full input deck into one of these messages? The screenshots are quite difficult to work with.

If you surround the deck with ``` markers, then the formatting will be usable for us:

For example:

```
begin:constant
x1 = 5
x2 = 7
end:constant
```

becomes

begin:constant
x1 = 5
x2 = 7
end:constant

Cheers,
Stuart