It covers basic knowledge about the principle, structure, performance, and applications of the most commonly developed optical switches including MEMS-based, beam-steering, liquid crystal-based, electro-optic, SOA-based, and thermo-optic categories. Solid-state optical switching (i. switching with no moving parts) can use devices based upon electro-optic materials such as lithium niobate (LiNbO 3). An electro-optic material is one whose refractive index changes significantly when an electric field is applied across it. ? limit switches prevent a hoist hook from impacting a hoist or boom, which would cause damage to the wire rope or chain and potentially overload the motor. A hoist's input shaft. Optical switches, pivotal components in modern photonics and optical communication systems, dynamically control the routing of light signals by altering their transmission paths.