Simulating structure and optical response of vacuum evaporated porous rugate filters

The drive to develop better thin film devices stimulates great interest in the understanding and control of the properties and morphology of films. In this article we present a study of the optical response of thin film interference filters, utilizing both experimental tools and computer simulation. The filters were deposited onto flat substrates in high vacuum with the technique of glancing angle deposition, which produces complex film structures with nanometer scale pores. A three-dimensional Monte Carlo simulator accurately reproduced this complicated morphology, while also providing information about nucleation, structure evolution, and packing density. Finally, the results of the computer modeling were used to optimize the effects of process parameters to minimize the difference between the design and the observed optical responses, thus providing a powerful tool for improving the performance of optical devices.