# Meep

Meep is a free finite-difference time-domain (FDTD) simulation software package to model electromagnetic systems. Meep is an acronym which officially stands for MIT Electromagnetic Equation Propagation. Its features include:

• Free software under the GNU GPL.
• Simulation in 1d, 2d, 3d, and cylindrical coordinates.
• Distributed memory parallelism on any system supporting the MPI standard. Portable to any Unix-like operating system such as Linux and MacOS.
• Arbitrary anisotropic electric permittivity $\varepsilon$ and magnetic permeability $\mu$, along with dispersive $\varepsilon(\omega)$ and $\mu(\omega)$ including loss/gain and nonlinear (Kerr & Pockels) dielectric and magnetic materials, and electric/magnetic conductivities $\sigma$.
• PML absorbing boundaries and/or perfect conductor and/or Bloch-periodic boundary conditions.
• Exploitation of symmetries to reduce the computation size — even/odd mirror symmetries and 90°/180° rotations.
• Complete scriptability — either via a Scheme scripting front-end via libctl, or callable as a C++ library. An official Python interface is under development.
• Field output in the HDF5 standard scientific data format, supported by many visualization tools.
• Arbitrary material and source distributions.
• Field analyses including flux spectra, Maxwell stress tensor, frequency extraction, local density of states and energy integrals, near to far field transformations; completely programmable.
• Multi-parameter optimization, root-finding, integration, etcetera via libctl and/or NLopt.

## Time-Domain Simulation

A time-domain electromagnetic simulation simply takes Maxwell's equations and evolves them over time within some finite computational region, essentially performing a kind of numerical experiment. This can be used to calculate a wide variety of useful quantities, but major applications include:

• Transmission and Reflection Spectra — by Fourier-transforming the response to a short pulse, a single simulation can yield the scattering amplitudes over a wide spectrum of frequencies.
• Resonant Modes and Frequencies — by analyzing the response of the system to a short pulse, one can extract the frequencies, decay rates, and field patterns of the harmonic modes of lossy and lossless systems including waveguide and cavity modes.
• Field Patterns (e.g. Green's functions) in response to an arbitrary source, archetypically a CW (fixed-$\omega$) input.

Using these results, one can then compute many other things, such as the local density of states from the trace of the Green's function. Meep's scriptable interface makes it possible to combine many sorts of computations along with multi-parameter optimization etcetera in sequence or in parallel.

Tutorial/Basics gives examples of all of these kinds of computations.

The latest development sources are available on GitHub. The source tarballs are available on the Download page. The release history is described in the Release Notes. The installation instructions can be found in the Installation page.

## Documentation

See the navigation sidebar at left. In particular, the Introduction and Tutorial are the most important things to read. We also have an FAQ.

Please cite Meep in any publication for which you found it useful.

### Mailing Lists

Subscribe to the read-only meep-announce mailing list to receive notifications of updates and releases. Subscribe to the meep-discuss mailing list for discussions about using Meep. Archives are available here. You can also read and post to the list via the gmane.comp.science.electromagnetism.meep.general newsgroup from Gmane.

### Bug Reports and Feature Requests

For bug reports and feature requests, please file a Meep GitHub issue.

## Acknowledgements

The Meep project is maintained by Simpetus and the open-source community on GitHub. Please see the Acknowledgements for a more complete listing of those to whom we are grateful.

## Contacts and Feedback

If you have questions or problems regarding Meep, you are encouraged to query the mailing list.

Professional consulting services as well as free access to Meep in the public cloud via Amazon Web Services (AWS) are provided by Simpetus.