# SPDX-FileCopyrightText: 2026 John C. Travers and contributors
#
# SPDX-License-Identifier: GPL-3.0-or-later

r"""
Supercontinuum in a photonic crystal fibre
==========================================

The canonical solid-core supercontinuum: a 50 fs, 10 kW sech pulse at 835 nm in 15 cm
of photonic crystal fibre, pumped in anomalous dispersion close to the zero-dispersion
wavelength. The parameters are those of Fig. 3 of the review by Dudley, Genty and Coen,
the standard test of a generalised nonlinear Schrödinger equation solver: the
fibre's dispersion as ten Taylor coefficients about the pump (beta_2 to beta_10),
gamma = 0.11 /W/m, self-steepening, and silica's Raman response.

The launch is a soliton of order N = 8.7. It compresses within the first centimetre
and then breaks up (soliton fission) into fundamental solitons, which shift to longer
wavelengths by the Raman effect, and dispersive waves phase-matched to them on the
short-wavelength side of the zero-dispersion wavelength.

**What to look for.** In the spectral map the continuum spreads to both sides at
fission, near 1 cm; the red-shifting solitons then curve away to beyond 1200 nm and
the dispersive waves gather near 500-600 nm. In the time domain the solitons, slowed
as they shift, walk off to positive delay.

**What is approximate.** The fibre is described by its dispersion and gamma at the
pump alone, as in the review: no wavelength dependence of the effective area beyond
self-steepening's. One seeded shot of input noise is propagated; the shot-to-shot
coherence the review studies with ensembles is not estimated here.

``Recipe.example("fibre_supercontinuum")`` is this run as a recipe.

Reference: J. M. Dudley, G. Genty and S. Coen, `Supercontinuum generation in photonic
crystal fiber <https://doi.org/10.1103/RevModPhys.78.1135>`_, Rev. Mod. Phys. 78,
1135-1184 (2006), section III and Fig. 3.
"""

# %%
# The run
# -------
# The Taylor coefficients are in s^n/m, about 835 nm. The 12.5 ps window holds the
# solitons as they walk off; 201 planes resolve the evolution along the fibre.

import time

from solprop.driver import prop_gnlse
from solprop.plotting import prop_2d, spec_1d

started = time.perf_counter()
output = prop_gnlse(
    0.11,
    0.15,
    [
        0.0,
        0.0,
        -11.830e-27,
        8.1038e-41,
        -9.5205e-56,
        2.0737e-70,
        -5.3943e-85,
        1.3486e-99,
        -2.5495e-114,
        3.0524e-129,
        -1.7140e-144,
    ],
    wavelength=835e-9,
    wavelength_limits=(400e-9, 2e-6),
    trange=12.5e-12,
    fwhm=50e-15,
    shape="sech",
    peak_power=10e3,
    raman=True,
    shock=True,
    n_save=201,
    seed=20261106,
    progress="none",
)
print(f"Propagated in {time.perf_counter() - started:.1f} s")

# %%
# The evolution along the fibre
# -----------------------------
# The spectral energy density in decibels beside the instantaneous power, against
# distance, as in the review's figure.
prop_2d(
    output,
    "wavelength",
    spec_range=(450e-9, 1350e-9),
    time_range=(-1e-12, 5e-12),
    db_min=-40.0,
)

# %%
# The spectrum at the exit
# ------------------------
spec_1d(output, 0.15, "wavelength", spec_range=(450e-9, 1350e-9), log_min=1e-4)

# %%
# Related reading
# ---------------
# The GNLSE and its terms are in :doc:`/guide/waveguides/gnlse`; the soliton this
# continuum breaks up from is the subject of
# :doc:`/introduction/lessons/plot_02_soliton`.