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)

Configuration

You can load parameters by simpling 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

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

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

capillray_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.

length: float, optional length of the fiber in m. 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 shape, either use one of 2 in (power, energy) together with one of 2 in (width, t0), or use soliton_num together with one of 4 in (power, energy, width, t0)

power: float peak power in W

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

solition_num: float soliton number

optional

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

Environment parameters

path_prefixes : dict[str, str] key : hostname (as returned by socket.gethostname()) value : path to the head's current working directory When running the simulations on multiple instances, the head's working directory needs to be mounted as a network drive on every other node, with its path specified with this parameter

Example:

[environment.path_prefixes]
Excellent_node = "Z:\\simulations\\"

this means that if I'm working on Average_node (i.e. Average_node is the head of the ray cluster) in `/Users/username/simulations/` and connecting Excellent_node (Windows) to the ray cluster, I need to be able to access Average_node's `simulations` directory by mounting it as a network drive. In this example, `username` is shared on the network by Average_node and Excellent_node is mounting it as a network share with the same credentials as Average_node's (to avoid permission problems). This means that `Z:\\simulations\` on Excellent_node points to the same directory as `/Users/username/simulations/` on Average_nodes. Jobs sent by the head's scgenerator module to Excellent_node will have an environment variable set so that Average_node's cwd so that files are all saved in the same place.