The ability to integrate micro-optical elements with movable structures and microactuators has opened up many new opportunities for optical and optoelectronic systems. It allows us to manipulate optical beams more effectively than conventional methods, and is scalable to large optical systems. Optical MEMS (microelectromechanical systems) have applications in display, sensing, and optical data storage. Recently, telecommunications have become the market driver for optical MEMS. Many different kinds of devices and systems have been reported, including optical switches, optical crossconnect wavelength division add/drop multiplexers, tunable filters/lasers/detectors, dispersion compensators and polarization dispersion compensators.