A generalized nonlinear Schr\"odinger Python module implementing different models of input pulse quantum noise

TL;DR

This paper introduces an open-source Python module for simulating ultrashort laser pulse propagation in nonlinear waveguides, emphasizing quantum noise modeling and coherence analysis, validated through supercontinuum generation examples.

Contribution

The software uniquely implements quantum noise models within the generalized nonlinear Schrödinger equation framework, enabling detailed analysis of pulse coherence and noise effects.

Findings

Successfully reproduces supercontinuum generation results

Provides tools for quantum noise and coherence analysis

Open-source implementation under MIT license

Abstract

We provide Python tools enabling numerical simulation and analysis of the propagation dynamics of ultrashort laser pulses in nonlinear waveguides. The modeling approach is based on the widely used generalized nonlinear Schr\"odinger equation for the pulse envelope. The presented software implements the effects of linear dispersion, pulse self-steepening, and the Raman effect. The focus lies on the implementation of input pulse shot noise, i.e. classical background fields that mimick quantum noise, which are often not thoroughly presented in the scientific literature. We discuss and implement commonly adopted quantum noise models based on pure spectral phase noise, as well as Gaussian noise. Coherence properties of the resulting spectra can be calculated. We demonstrate the functionality of the software by reproducing results for a supercontinuum generation process in a photonic crystal fiber, documented in the scientific literature. The presented Python tools are are open-source and released under the MIT license in a publicly available software repository.