Wrong laser wavelength when reading FBPIC output

[delaossa]

When reading a laser profile from an FBPIC OpenPMD file, a wrong central laser frequency is extracted by the field_to_envelope function.

This code snippet should reproduce the issue:

from lasy.profiles.from_openpmd_profile import FromOpenPMDProfile
from lasy.laser import Laser
from lasy.utils.laser_utils import compute_laser_energy

laser_profile = FromOpenPMDProfile(path='.',
                   iteration=1,
                   pol=(1, 0),
                   field='E',
                   coord='x',
                   theta=0,
                   )
print(f'lambda0 = {laser_profile.lambda0:.3e} m')

dimensions = "rt"
r = laser_profile.axes["r"]
t = laser_profile.axes["t"]
lo = (r.min(), t.min())
hi = (r.max(), t.max())
num_points = (len(r), len(t))
laser = Laser(dimensions, lo, hi, num_points, laser_profile)
energy = compute_laser_energy('rt', laser.grid)
print(f'Energy = {energy :.2f} J')
laser.show()

which reads this file (I needed to zip it because github does not allow uploading h5 files):
fbpic_data.zip

This FBPIC data has been obtained with this example -> https://fbpic.github.io/example_input/boosted_frame_script.html