absorbing_boundary.py 文件源码

def plot_spectrum(sys):
    """
    Plot the High Harmonic Generation spectrum
    """
    # Power spectrum emitted is calculated using the Larmor formula
    #   (https://en.wikipedia.org/wiki/Larmor_formula)
    # which says that the power emitted is proportional to the square of the acceleration
    # i.e., the RHS of the second Ehrenfest theorem

    N = len(sys.P_average_RHS)
    k = np.arange(N)

    # frequency range
    omegas = (k - N / 2) * np.pi / (0.5 * sys.t)

    # spectra of the
    spectrum = np.abs(
        # used windows fourier transform to calculate the spectra
        # rhttp://docs.scipy.org/doc/scipy/reference/tutorial/fftpack.html
        fftpack.fft((-1) ** k * blackman(N) * sys.P_average_RHS)
    ) ** 2
    spectrum /= spectrum.max()

    plt.semilogy(omegas / sys.omega_laser, spectrum)
    plt.ylabel('spectrum (arbitrary units)')
    plt.xlabel('frequency / $\\omega_L$')
    plt.xlim([0, 45.])
    plt.ylim([1e-15, 1.])