Welcome to pynumpm, short for PyNumericalPhasematching!

This package is meant to help you with the simulation of the phasematching spectrum of nonlinear processes, in particular of collinear three wave mixing processes. It can numerically calculate the phasematching of ideal waveguides and of waveguides with variable profile along their propagation axes. Moreover, it can calculate the phasematching as a function of the wavevector mismatch , of one scanning wavelength or of two scanning wavelength. This last functionality can be used for the calculation of joint spectral amplitude and intensity spectra and properties.

Notes

• All physical quantities in this package are expressed in SI units (m, s, rad/s).
• In this package, the wavelengths are usually denoted as red, green and blue (or r, g, b). This implies that the blue field has shortest wavelength and the red has the longest wavelength. In case two fields have the same wavelength, then the names are interchangeable.
• The functions describing the refractive indices, when used, must follow the convention of the standard Sellmeier's equation, i.e. they must accept the wavelength in .

pynumpm has been written for Python3, but this release should still work with Python2. Support for Python2 is not provided.

pynumpm requires the following python packages:

• pip
• numpy
• matplotlib
• scipy
• warnings
• logging

The setup will automatically take care of installing the missing packages, when possible.

The package by downloading the package from GitHub and, in the folder pynumericalphasematching, run

python setup.py install

The installation via PyPI will be available as soon as the package is stable.

The basic steps to run a simulation, are:

1. Create a waveguide object, using a suitable class from the waveguide module.
2. Create a phasematching object, using a suitable class from the phasematching module and loading the waveguide object into such object.
3. Run the calculate_phasematching() method of the phasematching object to calculate the phasematching spectrum.

Here, the first steps for setting up a simple simulation are described. For more information and tutorial, check the documentation.

The next code creates an ideal waveguide with length L = 10mm and a poling period of 4.4.

import numpy as np
from pynumpm import waveguide

thiswaveguide = waveguide.Waveguide(length = 1e-2,
                                    poling_period = 4.4e-6)                                          

The following lines load the Waveguide object created in the previous step into a PhasematchingDeltaBeta object and calculate the phasematching spectrum as a function of

deltabeta = np.linspace(-5000, 5000, 1000)
thisprocess = phasematching.PhasematchingDeltaBeta(waveguide=thiswaveguide)
thisprocess.deltabeta = deltabeta
thisprocess.calculate_phasematching()
thisprocess.plot()

For more example, consult the Tutorials in the documentation.

• TODO: replace rectangular integration in Phasematching 1D and 2D with the sinc (the correct integration)
• Insert bandwidth estimation (for 1D functions)
• TODO: Use FFT to calculate Simple 1D and 2D phasematching with user defined nonlinear profile (introduce in version 1.1).

The complete documentation of this package can be found here.

• Matteo Santandrea, University of Paderborn, Integrated Quantum Optics group

This project is licensed under the GNU GPLv3+ License - see the LICENSE.md file for details

• Benjamin Brecht, University of Paderborn (Pump() class)
• Marcello Massaro, University of Paderborn. Help with docstring, documentation, VCS, and cleaning up my messy work.

Please cite this package as PyNumericalPhasematching v1.0, 2019. The DOI of this package is 10.5281/zenodo.3538004