thunder4d.cell

The multipass cell. See Simulation for the unfolded picture, the eigenmode and the nonlinear mode matching.

class thunder4d.cell.MPC(R, d, medium, n_passes, *, mirror_gdd_fs2=0.0, mirror_tod_fs3=0.0, mirror_reflectivity=1.0, mirror_phase=None, mirror_diameter=None)

Symmetric two-mirror cell.

Parameters:

• R (float) – mirror radius of curvature [m]

• d (float) – mirror separation [m], \(0 < d < 2R\)

• medium – Material

• n_passes (int) – passes = bounces (transit over d + bounce, starting right after a mirror)

• mirror_gdd_fs2 (float) – GDD per bounce [fs²]

• mirror_tod_fs3 (float) – TOD per bounce [fs³]

• mirror_reflectivity – intensity reflectivity, scalar or callable R(lambda_m)

• mirror_phase (callable) – phi(lambda_m) [rad] per bounce (e.g. a measured GDD curve)

• mirror_diameter (float) – clear aperture [m] (soft super-Gaussian edge, order 30); None = infinite

Attributes: R, d, medium, n_passes, g (\(1 - d/R\)), theta (Gouy phase per pass [rad]).

classmethod herriott(R, N, k, medium, branch='concentric', n_passes=None, **kw)

Re-entrant Herriott cell that closes on itself after N passes: \(d = R[1+\cos(2\pi k/N)]\) (branch="concentric", default) or \(d = R[1-\cos(2\pi k/N)]\) (branch="planar"). The concentric branch requires an even N. n_passes defaults to N (one re-entrant cycle); set it to simulate any other number of passes in the same cell.

linear_mode(lam)

Linear eigenmode at wavelength lam.

Returns:

dict with w0, w_mirror, zR, gouy_per_pass

nonlinear_mode(P, lam, verbose=False)

Kerr-matched eigenmode for power P [W] at wavelength lam [m]. Raises ValueError if \(P \ge P_c\).

Returns:

dict

P, Pc, P_over_Pc	power, critical power, ratio
w0, w_mirror	matched waist and mirror spot [m]
w0_linear, w_mirror_linear	linear values [m]
B_per_pass, B_total	on-axis peak B-integral estimates [rad]
I_peak_center_W_cm2	peak intensity at the waist [W/cm²]

match(pulse, power='peak', verbose=True, lam=None)

Same as nonlinear_mode(), with the power and the wavelength taken from a Pulse: "peak" uses peak_power(), "weighted" uses weighted_power(). A number in W is also accepted, with its wavelength lam.

report(m=None)

Text summary of the cell and, optionally, of a matching dict.

mirror_spectrum(grid)

Spectral transfer of one bounce on grid.Omega: GDD, TOD, reflectivity and mirror_phase, zero outside the valid spectral window. Shape (Nt,).

mirror_aperture(r)

Amplitude transmission of the clear aperture at radius r [m] (soft super-gaussian edge of order 30); ones if mirror_diameter is None.

bounce_factor(grid)

Complex transfer of one mirror, shape grid.shape (cached): curvature, mirror_spectrum() and mirror_aperture().

bounce(Aw, grid)

Apply one mirror to Aw in place and return it.