Meep (or MEEP) 是一款 MIT 开发的，免费的 finite-difference time-domain (FDTD) 模拟软件包，可用来模拟电磁体系。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 system (GNU/Linux is fine).
• Dispersive ε(ω) (including loss/gain) and nonlinear (Kerr) materials.
• 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 (as in libctl and MPB), or callable as a C++ library.
• Field output in the HDF5 standard scientific data format, supported by many visualization tools.
• Arbitrary material and source distributions.
• Field analyses including flux spectra, frequency extraction, and energy integrals; completely programmable.
• Multi-parameter optimization, root-finding, integration, etcetera (via libctl).

感谢 Meep 的开发者 Steven G. Johnson ，以GNU GPL 方式发布该软件，也感谢他提供信息。他们还有其他一些相关软件，包括 MIT Photonic Bands (MPB) ，做光子晶体的人应该都了解。