Gaussian laser pulse#

We will try a simple example to get familiar with the code structure and to verify the installation was successful. Let’s generate a Gaussian pulse at focus, propagate it backwards by one Rayleigh length (the pulse is then located upstream of the focal plane) and then output it to a file.

First let’s load in the required functions from the library.

[1]:

from lasy.profiles.gaussian_profile import GaussianProfile
from lasy.laser import Laser

Next, define the physical parameters of the laser pulse and create the laser profile object.

[2]:

wavelength     = 800e-9  # Laser wavelength in meters
polarization   = (1,0)   # Linearly polarized in the x direction
energy         = 1.5     # Energy of the laser pulse in joules
spot_size      = 25e-6   # Waist of the laser pulse in meters
pulse_duration = 30e-15  # Pulse duration of the laser in seconds
t_peak         = 0.0     # Location of the peak of the laser pulse in time

laser_profile = GaussianProfile(wavelength,polarization,energy,spot_size,pulse_duration,t_peak)

Now create a full laser object containing the above physical parameters together with the computational settings.

[3]:

dimensions     = 'rt'                              # Use cylindrical geometry
lo             = (0,-2.5*pulse_duration)           # Lower bounds of the simulation box
hi             = (5*spot_size,2.5*pulse_duration)  # Upper bounds of the simulation box
num_points     = (300,500)                         # Number of points in each dimension

laser = Laser(dimensions,lo,hi,num_points,laser_profile)

The laser pulse can be visualized with the show method.

[4]:

laser.show()

/home/docs/checkouts/readthedocs.org/user_builds/lasydoc/envs/latest/lib/python3.11/site-packages/IPython/core/pylabtools.py:77: DeprecationWarning: backend2gui is deprecated since IPython 8.24, backends are managed in matplotlib and can be externally registered.
  warnings.warn(
/home/docs/checkouts/readthedocs.org/user_builds/lasydoc/envs/latest/lib/python3.11/site-packages/IPython/core/pylabtools.py:77: DeprecationWarning: backend2gui is deprecated since IPython 8.24, backends are managed in matplotlib and can be externally registered.
  warnings.warn(
/home/docs/checkouts/readthedocs.org/user_builds/lasydoc/envs/latest/lib/python3.11/site-packages/IPython/core/pylabtools.py:77: DeprecationWarning: backend2gui is deprecated since IPython 8.24, backends are managed in matplotlib and can be externally registered.
  warnings.warn(

../_images/tutorials_gaussian_laser_8_1.png

By default, the values of the laser envelope are injected on the focal plan. One can propagate it backwards by one Rayleigh length (optional).

[5]:

z_R            = 3.14159*spot_size**2/wavelength    # The Rayleigh length
laser.propagate(-z_R)                               # Propagate the pulse upstream of the focal plane

[6]:

laser.show()

../_images/tutorials_gaussian_laser_11_0.png

Output the result to a file. Here we utilise the openPMD standard.

[7]:

file_prefix    = 'test_output' # The file name will start with this prefix
file_format    = 'h5'          # Format to be used for the output file

laser.write_to_file(file_prefix, file_format)

The generated file may now be viewed or used as a laser input to a variety of other simulation tools.