You can download my paper about Inverse Problem for Photonic Crystals here:
Maximizing Band Gaps in Two-Dimensional Photonic Crystals by Using Level Set methods by Chiu Yen Kao, Stanley Osher, and Eli Yablonovitch
Incorporating Topological Derivatives into Shape Derivatives Based Level Set Methods by Lin He, Chiu-Yen Kao and Stanley Osher, IUCLA Math CAM Report 06-44 (2006)
