Getting started

Background

This API has been developed to solve the task of calculating the (one- or two-dimensional) phasematching spectrum of a wide variety of nonlinear optical processes processes. The package is best suited for the analysis of three-wave mixing phenomena; however, some of its tools can be used to study also higher-order optical nonlinear processes (four-wave mixing, etc.).

This API consists of four conceptually distinct modules:

  • the module pynumpm.waveguide is used to define the guiding structure under investigation. In here, one can define two types of guiding structures: ideal or real. An ideal structure is modelled as homogeneous along its z optical axis, whereas a real structure allows the definition of a profile describing the variation of its properties along the optical z axis;
  • the module pynumpm.noise is mostly used by the pynumpm.waveguide to model noisy structures. However, it can be accessed by the user, that can use its function to re-use the predefined noise profiles in case the basic functionalities provided in the pynumpm.waveguide are not enough;
  • the module pynumpm.phasematching is the core module of the API. It provides different types of functions for the calculation of phasematching spectra;
  • the module pynumpm.jsa provides classes that can be used to simulate the behaviour of the simulated phasematching when pumped with a pulsed light source. No quantum effects are taken into consideration and no time evolution has been taken into account. Therefore, this module works under the assumption of low nonlinear efficiency.

Installation

This package has been developed for Python3, but should work for Python2 as well. Support for Python2 is not provided.

It can be downloaded or cloned from its GitHub page. To install the package, simply run

python setup.py install

in the folder pynumericalphasematching.

As soon as possible, the package will be uploaded on PyPI.

Notes

Standards

This API requires all inputs to be in the base SI units (meters, Hertz) and returns results with the same conventions. For example, the code

wl = 1550e-9

defines a wavelength at 1550nm.

Definitions

It is necessary to be extremely careful when calculating processes using the dispersion relations of the material under investigation. Bear in mind two important conventions:

  1. The wavelength-dependent refractive index \(n(\lambda)\) must follow the convention of Sellmeier equations, i.e. it must accept the wavelength of the process in micrometers \(\mu\mathrm{m}\). Whenever the API needs to use the refractive index, it will automatically convert the wavelengths from meter [m] to micrometer [\(\mu\mathrm{m}\)].

  2. The refractive index of a structure having one parameter \(f\) changing along the propagation axis requires the definition of a refractive index function \(n(f)(\lambda)\), such that the call:

    n(f)

    returns a wavelength-dependent refractive index (consistent with the point 1.).

Logging

This package uses the logging module to log useful information.