The application and analysis of MEMS optical switches

Next-generation wavelength routing optical networks requiring optical cross connects (OXC) in the network have the ability to direct optical signals from any input interface to suitable output interfaces by configuring their internal embedded optical switch matrices. Optical switches based on MEMS technology have the fundamental advantage of being able to exploit the benefits of free-space interconnection (including low loss and crosstalk, and low polarization- and wavelength-dependence), together with the advantages of integrated optics (including compactness, optical pre-alignment, and low cost ). Therefore, it offers the possibility of achieving high port-count in a small, low-cost system with excellent optical quality. In this paper, at first the basic concepts of the two kinds of optical MEMS switches--2-D and 3-D switches are reviewed and the principle of the MEMS switches is introduced. The key parameter in the assembly/packaging of optical components is the insertion losses due to misalignment between the optical components. The misalignment losses are calculated as the coupling coefficient between two Gaussian beams having certain lateral and longitudinal separations and a tilt angle. It's concluded that optical design of a free-space MEMS component is a compromise between lateral misalignment and angular misalignment from the simulations. At last the application of optical MEMS switches in the optical cross-connects is discussed including the configurable WADM (wavelength-add-drop multiplexer) which can be achieved using 2-D MEMS crossbar matrix switches and the three-dimensional (3-D) microoptical switching system (3D-MOSS).