can laser deck generate plane wave?

[tomdg1626003]

hi developer
Under vacuum conditions, I used the laser module to generate a plane wave along the x direction and found that the amplitude of the wave was decreasing. Under this vacuum condition, the amplitude of the wave should be constant and should not decay. Is my setting or understanding incorrect?
begin:constant

laser_angle = 0 # Set angle of laser w.r.t positive x unit vector
laser_fwhm = 8.0e-6 # Size of gaussian profile for laser electric field
laser_wavelength = 1.0e-6
laser_k = 2 * pi / laser_wavelength

dt_snapshot = 5.e-15  

end:constant

begin:control

nx = 2000
ny = 1000

Final time of simulation

t_end = 100*dt_snapshot

t_end = 50.e-15
x_min = -10.0e-6
x_max = 10.0e-6
y_min = -10.0e-6
y_max = 10.0e-6
end:control

begin:boundaries

bc_x_min = simple_laser
bc_x_max = simple_outflow
bc_y_min = periodic
bc_y_max = periodic

bc_y_min = simple_outflow

bc_y_max = simple_outflow

end:boundaries

begin:laser

boundary = x_min
intensity_w_cm2 = 1.0e15
profile = gauss(y, 0, laser_fwhm)

profile = 0.1

profile = if(abs(y) gt 0.75, 0, cos(y2.0pi))

t_profile = 1

pol_angle = 0
phase = 0 # -y * laser_k * sin(pol_angle) # Vary wave-front position in space
lambda = 2laser_wavelength # cos(pol_angle) # Space wave-fronts apart correctly along k
t_start = 0.0
t_end = 100*dt_snapshot

end:laser

begin:output
dt_snapshot = 5.e-15
grid = always
ex = always
ey = always
ez = always
bx = always
by = always
bz = always

end:output

[ktangtar]

If you do the problem in 1d, it will automatically be a plane wave. Giving the laser a transverse size (you have a gaussian profile) will result in focusing/defocusing of the wave.

[Status-Mirror]

Hey @tomdg1626003,

I think the formatting has gone a bit weird on your input deck. On GitHub, you can write

```
This stuff
```

to make

This stuff

I'm going to assume your input deck is of the form I give at the end of this message, where some comments have been removed.

@ktangtar is correct - even though you have no temporal profile, the laser pulse itself will change shape as it propagates through your simulation window. To inject a simple plane wave, change profile in your laser block to match:

profile = 1

I'm going to mark this issue as solved, but feel free to continue messaging if you have any further problems.

Cheers,
Stuart

begin:constant
  laser_angle = 0 # Set angle of laser w.r.t positive x unit vector
  laser_fwhm = 8.0e-6 # Size of gaussian profile for laser electric field
  laser_wavelength = 1.0e-6
  laser_k = 2 * pi / laser_wavelength
  dt_snapshot = 5.e-15  
end:constant

begin:control
  nx = 2000
  ny = 1000
  t_end = 50.e-15
  x_min = -10.0e-6
  x_max = 10.0e-6
  y_min = -10.0e-6
  y_max = 10.0e-6
end:control

begin:boundaries
  bc_x_min = simple_laser
  bc_x_max = simple_outflow
  bc_y_min = periodic
  bc_y_max = periodic
end:boundaries

begin:laser
  boundary = x_min
  intensity_w_cm2 = 1.0e15
  profile = gauss(y, 0, laser_fwhm)
  pol_angle = 0
  phase = 0
  lambda = 2 * laser_wavelength
  t_start = 0.0
  t_end = 100*dt_snapshot
end:laser

begin:output
  dt_snapshot = 5.e-15
  grid = always
  ex = always
  ey = always 
  ez = always
  bx = always 
  by = always
  bz = always
end:output