Meep is a free/open-source, finite-difference time-domain (FDTD), software package for simulating electromagnetic systems. Meep is an acronym which officially stands for MIT Electromagnetic Equation Propagation. Its features include:

• Free and open-source software under the GNU GPL.
• Complete scriptability via Python, Scheme, or C++.
• 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, 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.
• 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, arbitrary functions, near to far field transformations; completely programmable.

## 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. 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.

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 development repository is on GitHub. Gzipped tarballs of stable versions are available in Download. The release history is described in NEWS. Installation instructions are in Installation.

## Documentation

See the navigation sidebar at left. In particular, the Introduction and Tutorial/Basics are the most important things to review. There is also an FAQ.

Please cite the reference publication in any work for which you found Meep 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 regarding using Meep. The meep-discuss archives includes all postings since 2006 spanning a large number and variety of discussion topics related to installation, setting up simulations, post-processing output, etc.

### Bug Reports and Feature Requests

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

## Acknowledgements

The Meep project is maintained by Simpetus and the open-source developer community on GitHub. Acknowledgements provides a complete listing of the project contributors.

## Support and Feedback

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

Professional consulting services for photonic design and modeling including development of custom, turn-key simulation modules, training, technical support, and access to Meep in the public cloud via Amazon Web Services (AWS) are provided by Simpetus.