MIT Photonic-Bands: http://ab-initio.mit.edu/mpb
A program for computing photonic band structures, developed by Steven G. Johnson (stevenj@alum.mit.edu), originally in the Joannoupoulos Ab-Initio Physics group in the MIT Physics Department and now in MIT Applied Mathematics
See the MIT Photonic-Bands web page, for a complete description of the package and its user interface, as well as installation instructions, the license and copyright, contact addresses, and other important information.
To build MPB from git (on a Unix-like system), do:
git clone git://github.com/stevengj/mpb
cd mpb
sh autogen.sh
make
To build it, you will need various dependencies installed as described in the MPB Installation Manual.