An innovative 2 x 2 Optical Switch has been designed by GTE Fiber Optic Products as an electromechanical bypass product for Data Communication, Local Area Network, and Telecommunication applications. The switch provides a means for easily transferring optical signals from one fiber to another in a two by two or quad port configuration. GTE's design differs from others on the market in that it uses expanded beam technology with a sliding prism oriented to reduce lateral alignment sensitivity. This tolerance of misalignment results in notably consistent throughput - a feature not always found in electromechanical switches. The design calls for two input fibers on one side of the switch with two output fibers opposite. Because a loopback fiber is unnecessary, optical throughput is similar for all four beam paths. Other advantages include beam separation flexibility and a more rugged package. Using this technology, both latching and fail safe designs have been developed. Optical switches are increasingly being used to provide system protection and to aid in network testing during installations and troubleshooting. In Local Area Networks, particularly those of a ring configuration, 2 x 2 switches are also gaining acceptance as a technologically simple and smart way of isolating or alternately connecting parts of a fiber network without introducing high losses.