thunder4d.materials

Gas filling the cell.

class thunder4d.materials.Material(name, pressure_bar=1.0, temperature_K=293.15, *, n2_1bar=None, sellmeier=None, n_func=None, n2=None)

Parameters:

• name (str) – "He", "Ne", "Ar", "Kr", "Xe", "N2", "air", or any label if n_func is given

• pressure_bar (float) – pressure [bar]

• temperature_K (float) – temperature [K]; \(n^2-1\) scales as \(p/T\) and \(n_2\) as \(p \cdot 293.15/T\)

• n2_1bar (float) – override the tabulated \(n_2\) at 1 bar [m²/W]

• sellmeier (tuple) – override the coefficients (B1, C1, B2, C2) (λ in µm)

• n_func (callable) – n(omega) replacing the Sellmeier formula entirely

• n2 (float) – absolute \(n_2\) [m²/W] at the given conditions (no scaling)

Dispersion (Börzsönyi et al., Appl. Opt. 47, 4856, 2008):

\[n^2 - 1 = \frac{p}{p_0}\frac{T_0}{T}\left[\frac{B_1\lambda^2}{\lambda^2 - C_1} + \frac{B_2\lambda^2}{\lambda^2 - C_2}\right],\qquad p_0 = 1\ \text{bar},\ T_0 = 273.15\ \text{K}.\]

Warning

The tabulated \(n_2\) values (N2_1BAR) are approximate literature values (electronic Kerr only, no Raman). Replace them with your own.

n(omega)

Refractive index (1 for \(\omega \le 0\)).

k(omega)

Wavenumber \(n\omega/c\) [rad/m].

gvd(lam)

Group-velocity dispersion [fs²/m] at wavelength lam.

critical_power(lam)

\(P_c = \lambda^2/(2\pi n_0 n_2)\) [W] (Gaussian beam, aberration-free).

n2

\(n_2\) at the current pressure and temperature [m²/W].

thunder4d.materials.SELLMEIER

Dictionary of Sellmeier coefficients (B1, C1, B2, C2) per gas.

thunder4d.materials.N2_1BAR

Dictionary of \(n_2\) at 1 bar [m²/W] per gas (approximate).