pySFA

Python library for computing High-Order Harmonic Generation (HHG) spectra relying on the Strong Field Approximation (SFA) with saddle point.

Building

Create a new build folder, execute cmake and make

git clone git@github.com:rmhsik/pySFA.git
cd pySFA
mkdir build && cd build
cmake ..
make

API Reference

pySFA(Ip, efield, t, nthreads=1)

Compute the dipole response in time domain using the Strong-Field Approximation.

Parameter	Type	Description
`Ip`	`double`	Ionization potential of the atomic target in atomic units
`efield`	`double`	Real driving electric field array. It must be the same legnth as `t`. It must be in atomic units
`t`	`double`	Temporal array in atomic units
`nt`	`int`	Number of threads to perform the integration. Optional

Return	Type	Description
`dipole_array`	`complex`	Complex dipole response array in the temporal domain

Usage/Examples

import numpy as np
import matplotlib.pyplot as plt
from pySFA import pySFA

def sin2(t,tmax):
  '''
  Sin-squared temporal envelope
  '''
  env = 0
  if -tmax/2<t and t < tmax/2:
      env = np.sin(np.pi*(t-tmax/2)/tmax)**2
  return env

w0 = 0.057 # 800 nm wavelength in atomic untis
e0 = 0.067 # ~1.6x10^14 W/cm2 
period = 2*np.pi/w0

t,dt = np.linspace(-10*period,10*period, 8192,retstep=True)
n = t.shape[0]
tmax = 16*period
mask = np.array([sin2(ti,tmax) for ti in t])

efield = e0*mask*np.exp(1j*w0*t)

Ip = 0.578 # Ionization potential for Argon
dipole  = pySFA(Ip, efield, t, nthreads=16)

## Spectrum calculation
dw = 2*np.pi/(n*dt)
wmax = n*dw/2
w = np.arange(0,wmax,dw)
hhg_spectrum = np.abs(np.fft.rfft(dipole.real))**2

License