Silicon micromechanics including bulk micromachining and surface micromachining are an emerging field, which are beginning to impact almost every area of science and technology. Since the early days of fiber optics, it has been recognized that micro-optics was a fertile ground for the applications of microelectromechanical systems (MEMS). Mechanical movable structures and micromotors can be integrated on silicon using MEMS technology, which is finding its way into both large-scale and small-scale optical switches, variable optical attenuators, tunable lasers and filters, active equalizers, add/drop multiplexers, optical crossconnects, gain tilt equalizers, data transmitters and many others are beginning to find ubiquitous application in advanced lightwave systems. We are investigating the use of MEMS fabrication technology for applications in optical communications. Also we will describe what they are, how they are built and show how they have the potential to revolutionize lightwave systems. Using silicon microfabrication to produce optical components provides some compelling advantages. First, the silicon surface when treated properly can provide an optical surface of extremely high quality. Second, single-crystal silicon allow fabrication of fatigue-free devices since it has no dislocation. Third, the electrical properties of silicon allow for the integration of sensors and detectors with extraordinarily high precision. In addition, the require forces provided by microactuators have very limited force capabilities, and often the required displacements in many applications are also quite small, on the order of a wavelength (a few microns), which again provides a good match for the capabilities of MEMS. Finally, the lithographic batch fabrication of these devices, driven and made possible by the infrastructure of the IC industry, provides a relatively inexpensive fabrication method.