Optical modeling of MEMS

The theory and modeling of optical MEMS structures are discussed in this chapter. Optics is also related to the processing of silicon MEMS in many ways, but here the focus is on the optical MEMS structures themselves and not on their fabrication methods. A typical example of optical MEMS (or micro-optical-electromechanical systems) is a movable mirror on silicon, but the discussion is extended to nonmovable optical structures that have processing methods similar to MEMS. This chapter first presents the most relevant optical properties of silicon and the ways to manipulate them, followed by a short analysis of other related materials. Then a theoretical background for designing optical MEMS is provided, covering geometrical optics, matrix optics, scalar waves, Fourier transforms, electromagnetic optics, and quantum optics. Finally the numerical modeling methods for optical MEMS are explained, reaching from simple ray tracing to rigorous finite difference methods. The theoretical and numerical methods are illustrated with a number of example components, such as lenses, mirrors, waveguides, thin-film stacks, pixel detectors, and gratings.