In telecommunication, an optical switch is a switch that enables signals in optical fibers or integrated optical circuits (IOCs) to be selectively switched from one circuit to another. It may be characterized by switching speed, coupling loss, and connectivity. Additionally, cost, reliability, and durability over switching lifetime are also important design considerations for this switch. An optical switch may operate by mechanical means, such as physically shifting an optical fiber to drive one or more alternative fibers, or by electro-optic effects, magneto-optic effects, or other methods. Slow optical switches, such as those using moving fibers, may be used for alternate routing of an optical transmission path, such as routing around a fault. Fast optical switches, such as those using electro-optic or magneto-optic effects, may be used to perform logic operations; also included in this category are the semiconductor optical amplifiers, which are optoelectronic devices that can be used as optical switches and be integrated with discrete or integrated microelectronic circuits.