This two input two output type optical switch includes four one input two output type optical switches which are arranged to oppose one another, each of these one input two output type optical switches including a Y branch portion in which one optical waveguide is branched into two optical waveguides....http://www.google.com/patents/US7046872?utm_source=gb-gplus-sharePatent US7046872 - Optical switch, optical add-drop module, and optical communication system
