scgenerator/README.md

It is recommended to import scgenerator in the following manner : import scgenerator as sc

How to run a set of simulations

create a config file

run sc.parallel_simulations(config_file) or sc.simulate(config_file)

How to analyse a simulation

load data with the load_sim_data method spectra, params = load_sim_data("varyTechNoise100kW_sim_data") to plot plot_results_2D(spectra[0], (600, 1450, nm), params)

Environment variables

SCGENERATOR_PBAR_POLICY : "none", "file", "print", "both", optional whether progress should be printed to a file ("file"), to the standard output ("print") or both, default : print

Configuration

You can load parameters by simply passing the path to a toml file to the appropriate simulation function. Each possible key of this dictionary is described below. Every value must be given in standard SI units (m, s, W, J, ...) The configuration file can have a name parameter at the root and must otherwise contain the following sections with the specified parameters. Every section ("fiber", "gas", "pulse", "simulation") can have a "variable" subsection where parameters are specified in a list INSTEAD of being specified as a single value in the main section. This has the effect of running one simulation per value in the list. If many parameters are variable, all possible combinations are ran. Examples :

[fiber]
n2 = 2.2e-20

a single simulation is ran with this value

[fiber.variable]
n2 = [2.1e-20, 2.4e-20, 2.6e-20]

3 simulations are ran, one for each value

[fiber]
n2 = 2.2e-20
[fiber.variable]
n2 = [2.1e-20, 2.4e-20, 2.6e-20]

NOT ALLOWED

note : internally, another structure with a flattened dictionary is used

Fiber parameters

If you already know the Taylor coefficients corresponding to the expansion of the beta2 profile, you can specify them and skip to "Other fiber parameters":

beta: list-like list of Taylor coefficients for the beta_2 function

If you already have a dispersion curve, you can convert it to a npz file with the wavelength (key : 'wavelength') in m and the D parameter (key : 'dispersion') in s/m/m. You the refer to this file as

dispersion_file : str path to the npz dispersion file

else, you can choose a mathematical fiber model

model: str {"pcf", "marcatili", "marcatili_adjusted", "hasan"}

PCF : solid core silica photonic crystal fiber, as modeled in Saitoh, Kunimasa, and Masanori Koshiba. "Empirical relations for simple design of photonic crystal fibers." Optics express 13.1 (2005): 267-274.

marcatili : Marcatili model of a capillary fiber : Marcatili, Enrique AJ, and R. A. Schmeltzer. "Hollow metallic and dielectric waveguides for long distance optical transmission and lasers." Bell System Technical Journal 43.4 (1964): 1783-1809.

marcatili_adjusted : Marcatili model of a capillary fiber with adjusted effective radius in the longer wavelength : Köttig, F., et al. "Novel mid-infrared dispersive wave generation in gas-filled PCF by transient ionization-driven changes in dispersion." arXiv preprint arXiv:1701.04843 (2017).

hasan : Hasan model of hollow core anti-resonance fibers : Hasan, Md Imran, Nail Akhmediev, and Wonkeun Chang. "Empirical formulae for dispersion and effective mode area in hollow-core antiresonant fibers." Journal of Lightwave Technology 36.18 (2018): 4060-4065.

and specify the parameters it needs

pcf :

pitch: float distance between air holes in m pitch_ratio: float 0.2 < pitch_ratio < 0.8 ratio hole diameter/pich

marcatili, marcatili_adjusted, hasan :

core_radius: float radius of the hollow core in m

marcatili, marcatili_adjusted :

he_mode: list, shape (2, ), optional mode of propagation. default is (1, 1), which is the fundamental mode

marcatili_adjusted :

fit_parameters: list, shape (2, ), optional parameters for the effective radius correction. Defaults are (s, h) = (0.08, 200e-9) as in the referenced paper.

hasan :

capillary_num : int number of capillaries

capillary_outer_d : float, optional if g is specified outer diameter of the capillaries

capillary_thickness : float thickness of the capillary walls

capillary_spacing : float, optional if d is specified spacing between the capillary

capillary_resonance_strengths : list, optional list of resonance strengths. Default is []

capillary_nested : int, optional how many nested capillaries. Default is 0

Other fiber parameters :

gamma: float, optional unless beta is directly provided nonlinear parameter in m^2 / W. Will overwrite any computed gamma parameter.

effective_mode_diameter : float, optional effective mode field diameter in m

n2 : float, optional non linear refractive index

A_eff : float, optional effective mode field area

length: float, optional length of the fiber in m. default : 1

input_transmission : float number between 0 and 1 indicating how much light enters the fiber, useful when chaining many fibers together, default : 1

Gas parameters

this section is completely optional and ignored if the fiber model is "pcf"

gas_name: str name of the gas. default : "vacuum"

pressure: float pressure of the gas in the fiber. default : 1e5

temperature: float temperature of the gas in the fiber. default : 300

plasma_density: float constant plasma density (in m^-3). default : 0

Pulse parameters:

Mandatory

wavelength: float pump wavelength in m

To specify the initial pulse properties, either use one of 3 in (peak_power, energy, mean_power) together with one of 2 in (width, t0), or use soliton_num together with one of 5 in (peak_power, mean_power, energy, width, t0)

peak_power : float peak power in W

mean_power : float mean power of the pulse train in W. if specified, repetition_rate must also be specified

repetition_rate : float repetition rate of the pulse train in Hz

energy: float total pulse energy in J

width: float full width half maximum of the pulse in s. Will be converted to appropriate t0 depending on pulse shape

t0: float pulse width parameter

soliton_num: float soliton number

optional

field_file : str if you have an initial field to use, convert it to a npz file with time (key : 'time') in s and electric field (key : 'field') in sqrt(W) (can be complex). You the use it with this config key. You can then scale it by settings any 1 of mean_power, energy and peak_power (priority is in this order)

quantum_noise: bool whether or not one-photon-per-mode quantum noise is activated. default : False

intensity_noise: float relative intensity noise

shape: str {"gaussian", "sech"} shape of the pulse. default : gaussian

Simulation parameters

2 of 3

dt: float resolution of the temporal grid in s

t_num: int number of temporal grid points

time_window: float total length of the temporal grid in s

optional

behaviors: list of str {"spm", "raman", "ss"} spm is self-phase modulation raman is raman effect ss is self-steepening default : ["spm", "ss"]

raman_type: str {"measured", "stolen", "agrawal"} type of Raman effect. Default is "agrawal".

ideal_gas: bool if True, use the ideal gas law. Otherwise, use van der Waals equation. default : False

z_num : int number of spatial grid points along the fiber. default : 128

frep: float repetition rate in Hz. Only useful to convert units. default : 80e6

tolerated_error: float relative tolerated step-to-step error. default : 1e-11

step_size: float if given, sets a constant step size rather than adapting it.

parallel: bool whether to run simulations in parallel with the available ressources. default : false

repeat: int how many simulations to run per parameter set. default : 1

lower_wavelength_interp_limit: float dispersion coefficients are computed over a certain wavelength range. This parameter sets the lowest end of this range. If the set value is lower than the lower end of the wavelength window, it is raised up to that point. default : 0

upper_wavelength_interp_limit: float dispersion coefficients are computed over a certain wavelength range. This parameter sets the lowest end of this range. If the set value is higher than the higher end of the wavelength window, it is lowered down to that point. default : 1900e-9