# LaserFields

`LaserFields.jl`

is a library to describe the time-dependent electric fields of
a laser pulse. It implements the same pulse shapes and most of the features of
the laserfields library written in
Fortran. Please see the documentation of that library for the parameter
meanings, conventions used, etc. In particular, the "main" constructor
`LaserField(; kwargs...)`

accepts the same parameters as the Fortran library
parameter files as keyword arguments, and returns an instance of a subtype of
the abstract base type `LaserField`

depending on the parameters. E.g., to create
a Gaussian pulse with a duration (defined as the FWHM of the intensity) of 6 fs,
a wavelength of 800 nm, a peak intensity of 1e14 W/cm^2, and with the peak at
time t=7fs, one should call

```
lf = LaserField(form="gaussianI", is_vecpot=true, lambda_nm=800,
intensity_Wcm2=1e16, duration_as=6000, peak_time_as=7000)
```

Given a `LaserField`

instance `lf`

, the functions `E_field(lf,t)`

,
`E_fourier(lf,ω)`

, `A_field(lf,t)`

, and `A_fourier(lf,ω)`

can be used to obtain,
respectively, the electric field as a function of time, its Fourier transform
(implemented for most pulse shapes), the vector potential as a function of time,
and its Fourier transform. Calling the instance as a function, `lf(t)`

returns
the electric field, i.e., is equivalent to `E_field(lf,t)`

. The notebooks in the
`examples`

folder show some ways to use the library, including how to define a
set of fields through a YAML configuration file.

The "effective" duration of the pulse for n-photon processes can be obtained as
`lf.Teff(n_photon)`

, which is the integral over the pulse intensity envelope to
the n-th power (i.e., electric field envelope to the (2n)th power) over the
pulse, see, e.g., https://doi.org/10.1103/PhysRevA.77.043420 (Eq. 14).